diff --git a/CHANGELOG.md b/CHANGELOG.md
index f1dfeaff2..690bb5d72 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,4 +1,6 @@
 # Changelog
+2026-08-27
+A016 (Book or Defer Appointment): documented support for `SERVICE_PROVIDER_CLINICIAN` and `SERVICE_PROVIDER_CLINICIAN_ADMIN` roles, including the "Triaged - Provider To Action" state precondition for these roles (RAA-9623)
 
 ## {{ ansible_date_time.date }}
 * Initial commit
diff --git a/sandbox/src/routes/stu3/bookOrDeferAppointment.js b/sandbox/src/routes/stu3/bookOrDeferAppointment.js
index 39c92ce9a..ec889e6af 100644
--- a/sandbox/src/routes/stu3/bookOrDeferAppointment.js
+++ b/sandbox/src/routes/stu3/bookOrDeferAppointment.js
@@ -10,7 +10,7 @@ module.exports = [
     path: '/FHIR/STU3/Appointment',
     handler: (request, h) => {
 
-      const allowedBusinessFunctions = ["REFERRING_CLINICIAN", "REFERRING_CLINICIAN_ADMIN"]
+      const allowedBusinessFunctions = ["REFERRING_CLINICIAN", "REFERRING_CLINICIAN_ADMIN", "SERVICE_PROVIDER_CLINICIAN", "SERVICE_PROVIDER_CLINICIAN_ADMIN"]
 
       const validationResult = validationUtils.validateBusinessFunction(request, h, allowedBusinessFunctions)
       if (validationResult) {
diff --git a/specification/components/stu3/schemas/endpoints/a016-book-or-defer-appointment.yaml b/specification/components/stu3/schemas/endpoints/a016-book-or-defer-appointment.yaml
index 98856c076..ff3870af2 100644
--- a/specification/components/stu3/schemas/endpoints/a016-book-or-defer-appointment.yaml
+++ b/specification/components/stu3/schemas/endpoints/a016-book-or-defer-appointment.yaml
@@ -13,12 +13,18 @@ description: |
   In order to use this endpoint you must be an authenticated e-RS user and use one of the following e-RS roles:
     - `REFERRING_CLINICIAN`
     - `REFERRING_CLINICIAN_ADMIN`
+    - `SERVICE_PROVIDER_CLINICIAN`
+    - `SERVICE_PROVIDER_CLINICIAN_ADMIN`
 
   You need to check if the service is directly bookable, indirectly bookable, or triage by either using [[HYPERLINK_A033]] or [[HYPERLINK_A035]]. You can then offer appropriate actions to authenticated users, i.e. the ability to book an appointment into a directly bookable service if an appointment slot is available, defer the booking responsibility to a directly bookable service if no appointment slot is available, refer a patient into a triage service.
   
   If the service is directly bookable, you need to retrieve available appointment slots for the service using [[HYPERLINK_A015]].
 
-  You need to use the Unique Booking Reference Number (UBRN) of a referral request in order to use this endpoint. 
+  You need to use the Unique Booking Reference Number (UBRN) of a referral request in order to use this endpoint.
+  
+  If `businessFunction` is `SERVICE_PROVIDER_CLINICIAN` or `SERVICE_PROVIDER_CLINICIAN_ADMIN`, the referral must be in the 'Not Booked' state (i.e. it has been redirected to a directly bookable or triage service and is awaiting a booking, deferral, or triage decision). Calling this endpoint as a Service Provider Clinician when the referral is not in this state will return a `422` error with error code `INVALID_REQUEST_STATE`.
+  
+  Where a `SERVICE_PROVIDER_CLINICIAN_ADMIN` (SPCA) is acting on behalf of a `SERVICE_PROVIDER_CLINICIAN` (SPC), the on behalf of user ID must be that of an appropriate SPC. You can use endpoint [[HYPERLINK_A040]] to determine which e-RS users a `SERVICE_PROVIDER_CLINICIAN_ADMIN` is allowed to work "on-behalf-of".
 
   ## Important note when deferring to provider
   
@@ -64,6 +70,7 @@ parameters:
   - $ref: '../headers/request/OdsCode.yaml'
   - $ref: '../headers/request/BusinessFunction.yaml'
   - $ref: '../headers/request/CorrelationID.yaml'
+  - $ref: '../headers/request/OnBehalfOfUserID.yaml'
 requestBody:
   required: true
   content:
diff --git a/tests/sandbox/stu3/test_a016_book_or_defer_appointment.py b/tests/sandbox/stu3/test_a016_book_or_defer_appointment.py
index cbe61221a..43dd77eb0 100644
--- a/tests/sandbox/stu3/test_a016_book_or_defer_appointment.py
+++ b/tests/sandbox/stu3/test_a016_book_or_defer_appointment.py
@@ -14,6 +14,8 @@ class TestBookOrDeferAppointment(SandboxTest):
     allowed_business_function_data = [
         "REFERRING_CLINICIAN",
         "REFERRING_CLINICIAN_ADMIN",
+        "SERVICE_PROVIDER_CLINICIAN",
+        "SERVICE_PROVIDER_CLINICIAN_ADMIN",
     ]
 
     authorised_actor_data = Actor.all(