Defining Availability

Alpha

Medplum Scheduling APIs are currently in alpha.

This guide covers how to configure availability using the SchedulingParameters extension — at both the actor level (per Schedule) and the service type level (via HealthcareService). It covers scheduling constraints, field-level inheritance, override behavior, timezone handling, and multi-resource scheduling patterns.

Parameters may be defined on a HealthcareService and shared amongst all Schedules that book that type of appointment. Each Schedule may also override these parameters to define behaviors specific to that schedule as needed.

The diagram below shows how availability can be defined at both

The actor level (via Schedule)
The service level (via HealthcareService)

The Scheduling Parameters Extension

All scheduling constraints are managed through a single consolidated extension: SchedulingParameters. This extension can appear on both HealthcareService (for shared configuration) and Schedule.

To use scheduling APIs for a Schedule and HealthcareService, at least one of them must define the duration attribute (used to set how long the scheduled appointment will last). There must be a timezone attribute, which may also be defined on the Schedule's actor. (See Timezone Resolution)

When using scheduling APIs to interact with multiple Schedule resources at once, they must be configured with matching duration, alignmentInterval, alignmentTimezone, and alignmentOffset parameters. For this reason, Medplum recommends that these parameters only be set on HealthcareService resources.

Extension Fields

Url	Type	Default Value	Description	`HealthcareService` usage notes	`Schedule` usage notes
`duration`	Duration	none	Determines how long the time increments for a Slot are		Recommended to prefer setting this on `HealthcareService`
`timezone`	Code	none	Specifies the timezone (IANA timezone identifier, e.g., `America/New_York`) for interpreting availability. When not set, falls back to the `Schedule.actor`'s timezone.
`bufferBefore`	Duration	0 minutes (no buffer needed)	Sets prep-time needed before appointment start. It must be free at booking time, and will be reserved with a Slot.
`bufferAfter`	Duration	0 minutes (no buffer needed)	Sets cleanup time needed after appointment end. It must be free at booking time, and will be reserved with a Slot.
`alignmentInterval`	Duration	60 minutes (appointments start on-the-hour)	Start times must align to this interval (e.g., every 15 minutes)		Recommended to prefer setting this on `HealthcareService`
`alignmentOffset`	Duration	0 minutes	Shifts allowed start times by this offset (e.g., with a 15-minute alignmentInterval and a 5-minute alignmentOffset, valid starts are :05, :20, :35, :50)		Recommended to prefer setting this on `HealthcareService`
`alignmentTimezone`	Code	'Etc/UTC'	Anchors the alignment grid to local midnight of the given timezone, keeping start times stable across DST transitions.		Recommended to prefer setting this on `HealthcareService`
`service`	`Reference(HealthcareService)`	none	Pointer to the `HealthcareService` that these parameters should override.	Not permitted
`availability`	Nested Extension	Always available	Weekly recurring availability windows. When set, appointments must fit inside these windows.	Not permitted (use `HealthcareService.availableTime` instead)

Example of the SchedulingParameters extension on a HealthcareService

{
  "url": "https://medplum.com/fhir/StructureDefinition/SchedulingParameters",
  "extension": [
    // Recommended: duration determines how long the time increments for a Slot are.
    // If not set here, must be defined on all related Schedules. To book on multiple
    // schedules at once, they must all match in this dimension.
    {
      "url": "duration",
      "valueDuration": {
        "value": 1,
        "unit": "h"
      }
    },

    // Recommended: Time alignment interval (appointment start time boundaries)
    // To book on multiple schedules at once, they must all match in this dimension.
    {
      "url": "alignmentInterval",
      "valueDuration": {
        "value": 15,
        "unit": "min",
        "system": "http://unitsofmeasure.org",
        "code": "min"
      }
    },

    // Recommended: Time alignment offset (shift from interval boundaries)
    // To book on multiple schedules at once, they must all match in this dimension.
    {
      "url": "alignmentOffset",
      "valueDuration": {
        "value": 0,
        "unit": "min",
        "system": "http://unitsofmeasure.org",
        "code": "min"
      }
    },

    // Optional: Timezone for anchoring the alignment grid to local midnight
    // Independent of `timezone`, which controls availability window interpretation
    {
      "url": "alignmentTimezone",
      "valueCode": "America/New_York"
    },

    // Optional: specify time zone for availability interpretation
    // Falls back to Schedule's actor time zone if not specified
    {
      "url": "timezone",
      "valueCode": "America/Los_Angeles"
    },


    // Optional: Buffer time required before appointment
    {
      "url": "bufferBefore",
      "valueDuration": {
        "value": 15,
        "unit": "min",
        "system": "http://unitsofmeasure.org",
        "code": "min"
      }
    },

    // Optional: Buffer time required after appointment
    {
      "url": "bufferAfter",
      "valueDuration": {
        "value": 10,
        "unit": "min",
        "system": "http://unitsofmeasure.org",
        "code": "min"
      }
    }
  ]
}

Example of the SchedulingParameters extension on a Schedule

{
  "url": "https://medplum.com/fhir/StructureDefinition/SchedulingParameters",
  "extension": [
    // Required on Schedule: you must specify what type of appointment these parameters apply to
    {
      "url": "service",
      "valueReference": {
        "reference": "HealthcareService/5d02acfd-fbe8-4537-84e4-31f5116be105",
        "display": "Bariatric Surgery"
      }
    },

    // Optional: specify time zone for availability interpretation
    // Falls back to Schedule's actor time zone if not specified
    {
      "url": "timezone",
      "valueCode": "America/Los_Angeles"
    },

    // Optional: duration determines how long the time increments for a Slot are.
    // If not set here, must be defined on the related HealthcareService
    {
      "url": "duration",
      "valueDuration": {
        "value": 1,
        "unit": "h"
      }
    },

    // Recurring availability (Schedule only)
    {
      "url": "availability",
      "extension": [
        {
          "url": "availableTime",
          "extension": [
            { "url": "daysOfWeek", "valueCode": "mon" },
            { "url": "daysOfWeek", "valueCode": "wed" },
            { "url": "daysOfWeek", "valueCode": "fri" },
            { "url": "availableStartTime", "valueTime": "09:00:00" },
            { "url": "availableEndTime", "valueTime": "17:00:00" }
          ]
        }
      ]
    },

    // Buffer time before appointment
    {
      "url": "bufferBefore",
      "valueDuration": {
        "value": 15,
        "unit": "min",
        "system": "http://unitsofmeasure.org",
        "code": "min"
      }
    },

    // Buffer time after appointment
    {
      "url": "bufferAfter",
      "valueDuration": {
        "value": 10,
        "unit": "min",
        "system": "http://unitsofmeasure.org",
        "code": "min"
      }
    },

    // Time alignment interval (appointment start time boundaries)
    {
      "url": "alignmentInterval",
      "valueDuration": {
        "value": 15,
        "unit": "min",
        "system": "http://unitsofmeasure.org",
        "code": "min"
      }
    },

    // Time alignment offset (shift from interval boundaries)
    {
      "url": "alignmentOffset",
      "valueDuration": {
        "value": 0,
        "unit": "min",
        "system": "http://unitsofmeasure.org",
        "code": "min"
      }
    },

    // Timezone for anchoring the alignment grid to local midnight
    // Independent of `timezone`, which controls availability window interpretation
    {
      "url": "alignmentTimezone",
      "valueCode": "America/New_York"
    }
  ]
}

Alignment grid

Medplum Scheduling APIs generate possible appointments by projecting a repeating daily grid. These parameters control that grid:

Parameter	Description	Default
`alignmentInterval`	How frequently slot start times occur	60 minutes
`alignmentOffset`	Shifts slot start times by this amount	0 minutes
`alignmentTimezone`	What timezone the grid is anchored to	`Etc/UTC`

`alignmentInterval`

Sets how frequently appointments may begin. For back-to-back scheduling without gaps, set this value to match the duration parameter.

`alignmentOffset`

Example: to align your appointments starting at 9:15, 10:15, ..., set alignmentOffset to 15 minutes (with a 60-minute alignmentInterval).

`alignmentTimezone`

When clocks change for DST, slots appear to shift by an hour in local time — for example, a 9:00am slot may appear at 8:00am or 10:00am. Setting alignmentTimezone anchors the grid to local midnight instead, keeping slot times consistent year-round.

Relationship to timezone: The two fields serve distinct purposes and can be set independently:

timezone — which timezone to use when reading availableStartTime/availableEndTime values
alignmentTimezone — which timezone's midnight to use as the alignment grid anchor

The rare case in which they differ: a provider whose availability hours and appointment grid are managed in different timezones.

Actor Level Availability

The Concept of Implicit Availability

Medplum's scheduling model uses implicit availability: time is assumed to be free by default. You define availability rules using extensions that specify when resources are available based on recurring patterns. Slot resources are only used for explicit overrides—either to mark time as busy (when an appointment is booked) or to block out unavailable time.

This approach avoids the need to pre-generate thousands of Slot resources for every possible time slot. Instead, the system calculates available windows dynamically based on the availability rules you define.

The Schedule Resource

The Schedule resource is the foundation for defining actor-level availability for a provider, location, or device.

The Schedule resource should define the service types that it is capable of acting on in its serviceType attribute.

Here is an example of a Schedule resource that defines availability for a Practitioner.

{
  "resourceType": "Schedule",
  "id": "dr-smith-schedule",
  "actor": [{"reference": "Practitioner/dr-smith"}],
  "serviceType": [
    {
      "text": "Office Visit",
      "coding": [
        { "code": "office-visit" }
      ],
      "extension": [
        {
          "url": "https://medplum.com/fhir/service-type-reference",
          "valueReference": {
            "reference": "HealthcareService/23c3f1cc-4f55-4990-9775-511b02487e7e",
            "display": "Office Visit"
          }
        }
      ]
    }
  ],
  "extension": [{
    "url": "https://medplum.com/fhir/StructureDefinition/SchedulingParameters",
    "extension": [
      {
        "url": "service",
        "valueReference": {
            "reference": "HealthcareService/23c3f1cc-4f55-4990-9775-511b02487e7e",
            "display": "Office Visit"
        }
      },
      {
        "url": "duration",
        "valueDuration": {
          "value": 1,
          "unit": "h"
        }
      },
      {
        "url": "availability",
        "extension": [
          {
            "url": "availableTime",
            "extension": [
              { "url": "availableStartTime", "valueTime": "09:00:00" },
              { "url": "availableEndTime", "valueTime": "17:00:00" },
              { "url": "daysOfWeek", "valueCode": "mon" },
              { "url": "daysOfWeek", "valueCode": "tue" },
              { "url": "daysOfWeek", "valueCode": "wed" },
              { "url": "daysOfWeek", "valueCode": "thu" },
              { "url": "daysOfWeek", "valueCode": "fri" },
            ]
          }
        ]
      }
    ]
  }]
  //...
}

`availability` Extension

The availability sub-extension mirrors the FHIR R5+ Availability datatype shape. It is encoded using nested R4 extensions (because R4 does not have a native Availability data type). This is close to the R4 definition of HealthcareService.availabileTime, which is another possible source of scheduling availability data. If this sub-extension is not present, availability is constrained only by the presence of existing Slot resources for the schedule.

Sub-extension	Type	Description	Repeatable
`availableTime`	(nested)	One entry per availability window	Yes
↳ `daysOfWeek`	`valueCode`	One entry per day (`mon`–`sun`)	Yes
↳ `allDay`	`valueBoolean`	If `true`, window spans the full day	No
↳ `availableStartTime`	`valueTime`	Opening time (not allowed when `allDay` is present)	No
↳ `availableEndTime`	`valueTime`	Closing time (not allowed when `allDay` is present)	No
`notAvailableTime`	(nested)	Typed for future use; not yet processed	Yes

{
  "resourceType": "Schedule",
  "id": "dr-smith-schedule",
  "actor": [{"reference": "Practitioner/dr-smith"}],
  "serviceType": [
    {
      "text": "Office Visit",
      "coding": [
        { "code": "office-visit" }
      ],
      "extension":[
        {
          "url": "https://medplum.com/fhir/service-type-reference",
          "valueReference": {
            "reference": "HealthcareService/23c3f1cc-4f55-4990-9775-511b02487e7e",
            "display": "Office Visit"
          }
        }
      ]
    }
  ],
  "extension": [{
    "url": "https://medplum.com/fhir/StructureDefinition/SchedulingParameters",
    "extension": [
      {
        "url": "service",
        "valueReference": {
            "reference": "HealthcareService/23c3f1cc-4f55-4990-9775-511b02487e7e",
            "display": "Office Visit"
        }
      },
      {
        "url": "duration",
        "valueDuration": {"value": 1, "unit": "h"}
      },
      {
        "url": "availability",
        "extension": [
          {
            "url": "availableTime",
            "extension": [
              { "url": "daysOfWeek", "valueCode": "mon" },
              { "url": "daysOfWeek", "valueCode": "tue" },
              { "url": "daysOfWeek", "valueCode": "wed" },
              { "url": "daysOfWeek", "valueCode": "thu" },
              { "url": "daysOfWeek", "valueCode": "fri" },
              { "url": "availableStartTime", "valueTime": "09:00:00" },
              { "url": "availableEndTime",   "valueTime": "17:00:00" }
            ]
          }
        ]
      }
    ]
  }]
}

Service Level Availability

Service Types and HealthcareService

A HealthcareService gives a mechanism to define common scheduling parameters for an appointment type, which can then be used by multiple Practitioner's Schedules. This allows you to define standard appointment durations, buffer times, alignment intervals, and booking limits once and apply them across multiple providers.

For a Schedule to use the HealthcareService's scheduling parameters, the Schedule.serviceType must include a reference to the HealthcareService in its extensions.

{
  "resourceType": "HealthcareService",
  "id": "23c3f1cc-4f55-4990-9775-511b02487e7e",
  "type": [{
    "text": "Office Visit",
    "coding": [{
      "system": "http://example.org/appointment-types",
      "code": "office-visit"
    }]
  }],
  "availableTime": [
    "daysOfWeek": ["mon", "tue", "wed", "thu", "fri"],
    "availableStartTime": "09:00:00",
    "availableEndTime": "17:00:00"
  ],
  //...
  "extension": [{
    "url": "https://medplum.com/fhir/StructureDefinition/SchedulingParameters",
    "extension": [
      {
        "url": "duration",
        "valueDuration": {
          "value": 1,
          "unit": "h"
        }
      }
    ]
  }]
}

{
  "resourceType": "Schedule",
  "id": "dr-smith-schedule",
  "actor": [{"reference": "Practitioner/dr-smith"}],
  "serviceType": [
    {
      "text": "Office Visit",
      "coding": [
        { "code": "office-visit" }
      ],
      "extension":[
        {
          "url": "https://medplum.com/fhir/service-type-reference",
          "valueReference": {
            "reference": "HealthcareService/23c3f1cc-4f55-4990-9775-511b02487e7e",
            "display": "Office Visit"
          }
        }
      ]
    }
  ]
  //...
}

Override Behavior

A Practitioner's Schedule can override individual scheduling parameters for a specific service type by adding a SchedulingParameters extension that references that service. Only the fields explicitly set on the Schedule override the HealthcareService defaults — all other fields are inherited.

This means you only need to specify what differs. For example, to restrict availability to Tuesday and Thursday mornings while keeping all other parameters (duration, buffers, alignment) from the HealthcareService:

{
  "resourceType": "Schedule",
  "id": "dr-chen-schedule",
  "active": true,
  "actor": [{"reference": "Practitioner/dr-chen"}],
  "serviceType": [
    {
      "coding": [{"code": "new-patient-visit"}],
      "extension": [{
        "url": "https://medplum.com/fhir/service-type-reference",
        "valueReference": {
          "reference": "HealthcareService/f44bbf25-bf57-4263-8f10-be060cc91672",
          "display": "New Patient Visit"
        }
      }]
    }
  ],
  "extension": [
    {
      "url": "https://medplum.com/fhir/StructureDefinition/SchedulingParameters",
      "extension": [
        {
          "url": "service",
          "valueReference": {
            "reference": "HealthcareService/f44bbf25-bf57-4263-8f10-be060cc91672",
            "display": "New Patient Visit"
          }
        },
        // Only availability is overridden; duration, buffers, and alignment are inherited from HealthcareService
        {
          "url": "availability",
          "extension": [
            {
              "url": "availableTime",
              "extension": [
                { "url": "daysOfWeek", "valueCode": "tue" },
                { "url": "daysOfWeek", "valueCode": "thu" },
                { "url": "availableStartTime", "valueTime": "09:00:00" },
                { "url": "availableEndTime", "valueTime": "13:00:00" }
              ]
            }
          ]
        }
      ]
    }
  ]
}

Field-level inheritance: When a Schedule has a SchedulingParameters extension for a service, each field is resolved independently using this priority order (highest to lowest):

The field value from the Schedule's SchedulingParameters extension for that service
The field value from the HealthcareService's SchedulingParameters extension
The system default (0 for buffers and offset; 60 minutes for alignment interval; always-available for availability)
Per-actor timezone information (via Schedule.actor; only for timezone attribute)

If a Schedule has no SchedulingParameters extension at all, all parameters are inherited from this chain.

Blocking Time by Service Type

Here is an example of a Slot resource that blocks time for a specific service type.

{
  "resourceType": "Slot",
  "schedule": {"reference": "Schedule/dr-johnson-schedule"},
  "status": "busy-unavailable",
  "start": "2025-12-24T08:00:00Z",
  "end": "2025-12-27T07:59:59Z",
  "comment": "Holiday vacation",
  "serviceType": [{"coding": [{"code": "office-visit"}]}]
}

With serviceType: Blocks only that specific service
Without serviceType: Blocks all services

Timezone Resolution

Timezone per Scheduling Parameters Entry

The timezone parameter allows you to specify different timezones for different service types within the same Schedule. This is useful when a provider needs to define availability in different timezones for different services (e.g., a doctor who provides cardiac surgery where they might travel to in one time zone and call center availability in another time zone).

Fallback Logic: If no time zone is specified in the scheduling-parameters extension, then the availability will be interpreted in the time zone defined on the Schedule's actor reference (Practitioner, Location, or Device). It looks for the FHIR sanctioned time zone extension:

Adding a Timezone to an Actor

There is no native timezone field on Practitioner, Location, or Device, so you must add it via the FHIR timezone extension:

{
  resourceType: 'Practitioner',
  // ...
  extension: [
    {
      url: "http://hl7.org/fhir/StructureDefinition/timezone",
      valueCode: "America/Los_Angeles"
    }
  ]
}

Timezone Resolution Order:

If timezone is specified in the scheduling-parameters extension, use that time zone
Otherwise, fall back to the time zone defined on the Schedule's actor reference (Practitioner, Location, or Device)

Important Notes:

The time zone value should be an IANA time zone identifier (e.g., America/New_York, America/Los_Angeles, America/Miami)
When timezone is specified, all Time values in the availability extension are interpreted in that time zone

Here is an example of a Schedule with multiple service types, each with its own time zone:

{
  "resourceType": "Schedule",
  "id": "dr-smith-schedule",
  "actor": [{"reference": "Practitioner/dr-smith"}],
  "serviceType": [
    {
      "text": "Cardiac Surgery",
      "coding": [
        { "code": "cardiac-surgery" }
      ]
    },
    {
      "text": "Call Center Availability",
      "coding": [
        { "code": "call-center-availability" }
      ]
    }
  ],
  "extension": [
    {
      "url": "https://medplum.com/fhir/StructureDefinition/SchedulingParameters",
      "extension": [
        {
          "url": "service",
          "valueReference": {
            "reference": "HealthcareService/a8f88a98-2578-4644-b408-7ba73f104298",
            "display": "Cardiac Surgery"
          }
        },
        {
          "url": "timezone",
          "valueCode": "America/Los_Angeles"
        },
        {
          "url": "duration",
          "valueDuration": {
            "value": 1,
            "unit": "h"
          }
        },
        {
          "url": "availability",
          "extension": [
            {
              "url": "availableTime",
              "extension": [
                { "url": "daysOfWeek", "valueCode": "mon" },
                { "url": "daysOfWeek", "valueCode": "tue" },
                { "url": "daysOfWeek", "valueCode": "wed" },
                { "url": "availableStartTime", "valueTime": "11:00:00" }, // Interpreted in America/Los_Angeles
                { "url": "availableEndTime", "valueTime": "15:00:00" } // Interpreted in America/Los_Angeles
              ]
            }
          ]
        }
      ]
    },
    {
      "url": "https://medplum.com/fhir/StructureDefinition/SchedulingParameters",
      "extension": [
        {
          "url": "timezone",
          "valueCode": "America/New_York"
        },
        {
          "url": "service",
          "valueReference": {
            "reference": "HealthcareService/0dbe6bf1-40b8-4204-a406-f78b5a0e59d0"
            "display": "Call Center Availability"
          }
        },
        {
          "url": "duration",
          "valueDuration": {
            "value": 1,
            "unit": "h"
          }
        },
        {
          "url": "availability",
          "extension": [
            {
              "url": "availableTime",
              "extension": [
                { "url": "daysOfWeek", "valueCode": "mon" },
                { "url": "daysOfWeek", "valueCode": "tue" },
                { "url": "daysOfWeek", "valueCode": "wed" },
                { "url": "availableStartTime", "valueTime": "09:00:00" }, // Interpreted in America/New_York
                { "url": "availableEndTime", "valueTime": "17:00:00" } // Interpreted in America/New_York
              ]
            }
          ]
        }
      ]
    }
  ]
}

In this example:

Cardiac surgery availability is defined in America/Los_Angeles time zone (Mon-Wed 11am-3pm America/Los Angeles)
Call Center availability is defined in America/New_York time zone (Mon-Wed 9am-5pm Eastern)
Each service type's availability times are interpreted independently based on their respective timezones

Examples

Example 1: Simple Primary Care Office with Appointment Type Defaults

This example shows how to define availability for a simple primary care office where Practitioner's Schedules inherit default scheduling parameters from an HealthcareService.

HealthcareService: Office Visit Defaults

This HealthcareService defines default scheduling parameters for a 30-minute office visit with 5-minute buffers and 15-minute alignment intervals.

{
  "resourceType": "HealthcareService",
  "id": "office-visit",
  "type": [{
    "text": "Office Visit",
    "coding": [{
      "system": "http://example.org/appointment-types",
      "code": "office-visit",
      "display": "Office Visit"
    }]
  }],
  "extension": [{
    "url": "https://medplum.com/fhir/StructureDefinition/SchedulingParameters",
    "extension": [
      {
        "url": "duration",
        "valueDuration": {
          "value": 30,
          "unit": "min"
        }
      },
      {
        "url": "bufferBefore",
        "valueDuration": {"value": 5, "unit": "min"}
      },
      {
        "url": "bufferAfter",
        "valueDuration": {"value": 5, "unit": "min"}
      },
      {
        "url": "alignmentInterval",
        "valueDuration": {"value": 15, "unit": "min"}
      },
      {
        "url": "alignmentOffset",
        "valueDuration": {"value": 0, "unit": "min"}
      }
    ]
  }]
}

Schedule: Practitioner's Schedule without Overrides

This Schedule shows Dr. Johnson's availability (Mon-Fri 9am-5pm) that inherits all default parameters from the HealthcareService without any service-specific overrides.

{
  "resourceType": "Schedule",
  "id": "dr-johnson-schedule",
  "active": true,
  "actor": [{
    "reference": "Practitioner/dr-johnson",
    "display": "Dr. Sarah Johnson"
  }],
  "planningHorizon": {
    "start": "2025-01-01T00:00:00Z",
    "end": "2025-12-31T23:59:59Z"
  },
  "serviceType": [
    // This entry will allow using the office-visit shared HealthcareService definitions
    {
      "text": "Office Visit",
      "coding": [
        { "code": "office-visit" }
      ]
    }
  ],
  "extension": [
    // No values here, everything is inherited from shared definitions
  ]
}

Result: Dr. Johnson's schedule inherits all the default parameters from the HealthcareService for an office visit:

$find called with service-type=office-visit: For office visits, available to start every 15 minutes (:00, :15, :30, :45) with 5-minute buffers [from HealthcareService]

Example 2: Multi-Service Provider with Multiple Appointment Types and Overrides

A provider who offers different appointment types with varying availability and constraints. Overrides the default scheduling parameters for new patient visits.

HealthcareService: New Patient Visit

This HealthcareService defines a 60-minute new patient visit with 15-minute buffers, 30-minute alignment intervals, and a booking limit of 3 per day.

{
  "resourceType": "HealthcareService",
  "id": "new-patient-visit",
  "type": [{
    "text": "New Patient Visit",
    "coding": [{
      "system": "http://example.org/appointment-types",
      "code": "new-patient-visit",
      "display": "New Patient Visit"
    }]
  }],
  "extension": [{
    "url": "https://medplum.com/fhir/StructureDefinition/SchedulingParameters",
    "extension": [
      {
        "url": "duration",
        "valueDuration": {
          "value": 1,
          "unit": "h"
        }
      },
      {"url": "bufferBefore", "valueDuration": {"value": 15, "unit": "min"}},
      {"url": "bufferAfter", "valueDuration": {"value": 15, "unit": "min"}},
      {"url": "alignmentInterval", "valueDuration": {"value": 30, "unit": "min"}}
    ]
  }]
}

HealthcareService: Follow-up Visit

This HealthcareService defines a 20-minute follow-up visit with 5-minute buffers and 10-minute alignment intervals for more frequent scheduling.

It defines default availability of Monday-Friday, 9am-5pm.

{
  "resourceType": "HealthcareService",
  "id": "follow-up-visit",
  "type": {
    "text": "Follow-up Visit",
    "coding": [{
      "system": "http://example.org/appointment-types",
      "code": "follow-up",
      "display": "Follow-up Visit"
    }]
  },
  "availableTime": [{
    "daysOfWeek": ["mon","tue","wed","thu","fri"],
    "availableStartTime": "09:00:00",
    "availableEndTime": "17:00:00",
  }],
  "extension": [{
    "url": "https://medplum.com/fhir/StructureDefinition/SchedulingParameters",
    "extension": [
      {
        "url": "duration",
        "valueDuration": {
          "value": 20,
          "unit": "min"
        }
      },
      {"url": "bufferBefore", "valueDuration": {"value": 5, "unit": "min"}},
      {"url": "bufferAfter", "valueDuration": {"value": 5, "unit": "min"}},
      {"url": "alignmentInterval", "valueDuration": {"value": 10, "unit": "min"}}
    ]
  }]
}

Schedule: Multi-Service with Overrides

This schedule declares in its serviceType array that it can be booked for New Patient visits and Follow-Up visits.

This Schedule will use the default availability for the "Follow-Up" service (Mon-Fri 9am-5pm). It will override "New Patient Visit" appointment type to only be available on Tuesday and Thursday mornings (9am-1pm).

{
  "resourceType": "Schedule",
  "id": "dr-chen-schedule",
  "active": true,
  "actor": [{"reference": "PractitionerRole/dr-chen"}],
  "planningHorizon": {
    "start": "2025-01-01T00:00:00Z",
    "end": "2025-12-31T23:59:59Z"
  },
  "serviceType": [
    {
      "text": "New Patient Visit",
      "coding": [
        {
          "system": "http://example.org/appointment-types",
          "code": "new-patient-visit"
        }
      ],
      "extension": [
        "url": "https://medplum.com/fhir/service-type-reference",
        "valueReference": {
          "reference": "HealthcareService/new-patient-visit",
          "display": "New Patient Visit"
        }
      ]
    },
    {
      "text": "Follow-up Visit",
      "coding": [
        {
          "system": "http://example.org/appointment-types",
          "code": "follow-up"
        }
      ],
      "extension": [
        "url": "https://medplum.com/fhir/service-type-reference",
        "valueReference": {
          "reference": "HealthcareService/follow-up",
          "display": "Follow-up Visit"
        }
      ]
    }
  ],
  "extension": [
    // New patient visits only on Tuesday and Thursday mornings
    {
      "url": "https://medplum.com/fhir/StructureDefinition/SchedulingParameters",
      "extension": [
        {
          "url": "service",
          "valueReference": {
            "reference": "HeathcareService/new-patient-visit",
            dislpay: "New Patient Visit"
          }
        },
        {
          "url": "availability",
          "extension": [
            {
              "url": "availableTime",
              "extension": [
                { "url": "daysOfWeek", "valueCode": "tue" },
                { "url": "daysOfWeek", "valueCode": "thu" },
                { "url": "availableStartTime", "valueTime": "09:00:00" },
                { "url": "availableEndTime", "valueTime": "13:00:00" }
              ]
            }
          ]
        }
      ]
    }
  ]
}

Result:

New patient visits (ie. $find with the "New patient visit" HealthcareService): Tue/Thu 9am-1pm only, 60 minutes, can start every 30 minutes, 15-min buffers
Follow-ups (ie. $find called with the "Follow-up visit" HealthcareService): Mon-Fri 9am-5pm, 20 minutes, can start every 10 minutes, 5-min buffers

Example 3: Location-Specific Complex Surgical Scheduling

A bariatric surgery requiring surgeon, OR room, and anesthesiologist coordination.

HealthcareService: Bariatric Surgery

This HealthcareService defines scheduling for a 120-minute surgical procedure with 45/30-minute buffers and multiple booking limits (2 per day, 8 per week).

{
  "resourceType": "HealthcareService",
  "id": "bariatric-surgery",
  "type": [{
    "coding": [{
      "system": "http://snomed.info/sct",
      "code": "287809009",
      "display": "Bariatric Surgery"
    }]
  }],
  "extension": [{
    "url": "https://medplum.com/fhir/StructureDefinition/SchedulingParameters",
    "extension": [
      {
        "url": "duration",
        "valueDuration": {
          "value": 120,
          "unit": "min"
        }
      },
      {"url": "bufferBefore", "valueDuration": {"value": 45, "unit": "min"}},
      {"url": "bufferAfter", "valueDuration": {"value": 30, "unit": "min"}},
      {"url": "alignmentInterval", "valueDuration": {"value": 30, "unit": "min"}},
      {
        "url": "bookingLimit",
        "valueTiming": {
          "repeat": {"frequency": 2, "period": 1, "periodUnit": "d"}
        }
      },
      {
        "url": "bookingLimit",
        "valueTiming": {
          "repeat": {"frequency": 8, "period": 1, "periodUnit": "wk"}
        }
      }
    ]
  }]
}

Schedule: Surgeon Availability

This Schedule shows Dr. Martinez's availability for bariatric surgeries, limited to Tuesday and Thursday mornings (8am-4pm).

{
  "resourceType": "Schedule",
  "id": "surgeon-martinez-schedule",
  "active": true,
  "serviceType": [
    {
      "coding": [{"system": "http://snomed.info/sct", "code": "287809009"}]
      "extension": [{
        "url": "https://medplum.com/fhir/service-type-reference",
        "valueReference": { "reference": "HealthcareService/bariatric-surgery" }
      }]
    }
  ],
  "actor": [{
    "reference": "PractitionerRole/surgeon-martinez",
    "display": "Dr. Maria Martinez - Bariatric Surgeon"
  }],
  "extension": [{
    "url": "https://medplum.com/fhir/StructureDefinition/SchedulingParameters",
    "extension": [
      {
        "url": "service",
        "valueReference": { "reference": "HealthcareService/bariatric-surgery" }
      },
      {
        "url": "duration",
        "valueDuration": {
          "value": 1,
          "unit": "h"
        }
      },
      {
        "url": "availability",
        "extension": [
          {
            "url": "availableTime",
            "extension": [
              { "url": "daysOfWeek", "valueCode": "tue" },
              { "url": "daysOfWeek", "valueCode": "thu" },
              { "url": "availableStartTime", "valueTime": "08:00:00" },
              { "url": "availableEndTime", "valueTime": "16:00:00" }
            ]
          }
        ]
      }
    ]
  }]
}

Schedule: Operating Room Availability

This Schedule shows Operating Room 3's availability for surgical procedures, available weekdays 7am-7pm with extended 12-hour blocks.

{
  "resourceType": "Schedule",
  "id": "or-3-schedule",
  "active": true,
  "actor": [{
    "reference": "Location/or-3",
    "display": "Operating Room 3"
  }],
  "serviceType": [
    {
      "coding": [{"system": "http://snomed.info/sct", "code": "287809009"}]
      "extension": [{
        "url": "https://medplum.com/fhir/service-type-reference",
        "valueReference": { "reference": "HealthcareService/bariatric-surgery" }
      }]
    }
  ],
  "extension": [{
    "url": "https://medplum.com/fhir/StructureDefinition/SchedulingParameters",
    "extension": [
      {
        "url": "service",
        "valueReference": { "reference": "HealthcareService/bariatric-surgery" }
        }
      },
      {
        "url": "duration",
        "valueDuration": {
          "value": 1,
          "unit": "h"
        }
      },
      {
        "url": "availability",
        "extension": [
          {
            "url": "availableTime",
            "extension": [
              { "url": "daysOfWeek", "valueCode": "mon" },
              { "url": "daysOfWeek", "valueCode": "tue" },
              { "url": "daysOfWeek", "valueCode": "wed" },
              { "url": "daysOfWeek", "valueCode": "thu" },
              { "url": "daysOfWeek", "valueCode": "fri" },
              { "url": "availableStartTime", "valueTime": "07:00:00" },
              { "url": "availableEndTime", "valueTime": "19:00:00" }
            ]
          }
        ]
      }
    ]
  }]
}

Schedule: Anesthesiologist Availability

This Schedule shows Dr. Kim's availability for surgical procedures, covering weekdays 7am-5pm (10-hour blocks).

{
  "resourceType": "Schedule",
  "id": "anesthesiologist-kim-schedule",
  "active": true,
  "serviceType": [
    {
      "coding": [{"system": "http://snomed.info/sct", "code": "287809009"}]
      "extension": [{
        "url": "https://medplum.com/fhir/service-type-reference",
        "valueReference": { "reference": "HealthcareService/bariatric-surgery" }
      }]
    }
  ],
  "actor": [{
    "reference": "PractitionerRole/anesthesiologist-kim",
    "display": "Dr. James Kim - Anesthesiologist"
  }],
  "extension": [{
    "url": "https://medplum.com/fhir/StructureDefinition/SchedulingParameters",
    "extension": [
      {
        "url": "service",
        "valueReference": { "reference": "HealthcareService/bariatric-surgery" }
      },
      {
        "url": "duration",
        "valueDuration": {
          "value": 1,
          "unit": "h"
        }
      },
      {
        "url": "availability",
        "extension": [
          {
            "url": "availableTime",
            "extension": [
              { "url": "daysOfWeek", "valueCode": "mon" },
              { "url": "daysOfWeek", "valueCode": "tue" },
              { "url": "daysOfWeek", "valueCode": "wed" },
              { "url": "daysOfWeek", "valueCode": "thu" },
              { "url": "daysOfWeek", "valueCode": "fri" },
              { "url": "availableStartTime", "valueTime": "07:00:00" },
              { "url": "availableEndTime", "valueTime": "17:00:00" }
            ]
          }
        ]
      }
    ]
  }]
}

Result: When booking a bariatric surgery, the system queries all three schedules, calculates the intersection of availability, and creates atomic transaction bundles to book all required resources simultaneously.

Location Modeling

Location Hierarchy Pattern

Organization (Surgery Center)
  └─ Location (Building) [mode=kind]
       ├─ Location (Operating Rooms) [mode=kind, type=OR]
       │    ├─ Location (OR-1) [mode=instance]
       │    ├─ Location (OR-2) [mode=instance]
       │    └─ Location (OR-3) [mode=instance]
       └─ Location (Recovery Rooms) [mode=kind, type=RR]
            ├─ Location (Recovery-A) [mode=instance]
            └─ Location (Recovery-B) [mode=instance]

Specific vs. "Any Available" Room

Specific room required:

Query Schedule?actor=Location/or-3

Any OR room acceptable:

Query: Schedule?actor:Location.partof:Location.type=OR

Best Practices

1. Set Defaults on HealthcareService, Override Only What Differs on Schedule

Define duration, buffers, and alignment once on the HealthcareService. Only add a SchedulingParameters extension to a Schedule when that actor's availability or parameters differ from the service defaults. Omit any field that should be inherited.

2. Minimize Pre-Generated Slots

Only create Slot resources for:

Booked appointments (status: busy)
Blocked time (status: busy-unavailable)

Let $find calculate available windows dynamically.

3. Transaction Bundles for Multi-Resource Booking

Always use FHIR transaction bundles when booking appointments that require multiple resources to ensure atomicity.

The Scheduling Parameters Extension​

Extension Fields​

Alignment grid​

alignmentInterval​

alignmentOffset​

alignmentTimezone​

Actor Level Availability​

The Concept of Implicit Availability​

The Schedule Resource​

availability Extension​

Service Level Availability​

Service Types and HealthcareService​

Override Behavior​

Blocking Time by Service Type​

Timezone Resolution​

Timezone per Scheduling Parameters Entry​

Examples​

Example 1: Simple Primary Care Office with Appointment Type Defaults​

Example 2: Multi-Service Provider with Multiple Appointment Types and Overrides​

Example 3: Location-Specific Complex Surgical Scheduling​

Location Modeling​

Location Hierarchy Pattern​

Specific vs. "Any Available" Room​

Best Practices​

1. Set Defaults on HealthcareService, Override Only What Differs on Schedule​

2. Minimize Pre-Generated Slots​

3. Transaction Bundles for Multi-Resource Booking​