diff --git a/src/server/plugins/engine/options.js b/src/server/plugins/engine/options.js
index 41d8bce44..768d73a22 100644
--- a/src/server/plugins/engine/options.js
+++ b/src/server/plugins/engine/options.js
@@ -26,7 +26,8 @@ const pluginRegistrationOptionsSchema = Joi.object({
   saveAndExit: Joi.function().optional(),
   ordnanceSurveyApiKey: Joi.string().optional(),
   ordnanceSurveyApiSecret: Joi.string().optional(),
-  getLanguage: Joi.function().optional()
+  getLanguage: Joi.function().optional(),
+  generateReferenceNumber: Joi.function().optional()
 })
 
 /**
diff --git a/src/server/plugins/engine/plugin.ts b/src/server/plugins/engine/plugin.ts
index 941f63bd6..ca56fc050 100644
--- a/src/server/plugins/engine/plugin.ts
+++ b/src/server/plugins/engine/plugin.ts
@@ -8,6 +8,7 @@ import {
 
 import { type FormModel } from '~/src/server/plugins/engine/models/index.js'
 import { validatePluginOptions } from '~/src/server/plugins/engine/options.js'
+import { generateUniqueReference } from '~/src/server/plugins/engine/referenceNumbers.js'
 import { getRoutes as getFileUploadStatusRoutes } from '~/src/server/plugins/engine/routes/file-upload.js'
 import { makeLoadFormPreHandler } from '~/src/server/plugins/engine/routes/index.js'
 import { getRoutes as getPaymentRoutes } from '~/src/server/plugins/engine/routes/payment.js'
@@ -37,6 +38,7 @@ export const plugin = {
       cache,
       saveAndExit,
       getLanguage,
+      generateReferenceNumber,
       nunjucks: nunjucksOptions,
       viewContext,
       preparePageEventRequestOptions,
@@ -80,6 +82,10 @@ export const plugin = {
     server.expose('cacheService', cacheService)
     server.expose('saveAndExit', saveAndExit)
     server.expose('getLanguage', getLanguage)
+    server.expose(
+      'generateReferenceNumber',
+      generateReferenceNumber ?? generateUniqueReference
+    )
     server.expose('baseUrl', baseUrl)
     server.expose('services', services)
 
diff --git a/src/server/plugins/engine/referenceNumbers.ts b/src/server/plugins/engine/referenceNumbers.ts
index 2b4fde674..b7653916c 100644
--- a/src/server/plugins/engine/referenceNumbers.ts
+++ b/src/server/plugins/engine/referenceNumbers.ts
@@ -6,6 +6,8 @@ import {
   englishRecommendedTransformers
 } from 'obscenity'
 
+export const DEFAULT_REFERENCE_NUMBER = 'XXX-XXX-XXX'
+
 /**
  * To prevent confusion to users reading the reference number, ambiguous letters and numbers are removed.
  * @param strCodes - array of binary input values
diff --git a/src/server/plugins/engine/routes/index.ts b/src/server/plugins/engine/routes/index.ts
index e39d5e555..a17d34cf8 100644
--- a/src/server/plugins/engine/routes/index.ts
+++ b/src/server/plugins/engine/routes/index.ts
@@ -20,6 +20,7 @@ import {
   findPage,
   getCacheService,
   getPage,
+  getPluginOptions,
   getStartPath,
   proceed
 } from '~/src/server/plugins/engine/helpers.js'
@@ -28,7 +29,7 @@ import {
   checkSaveAndExitRepeater,
   copyNotYetValidatedState
 } from '~/src/server/plugins/engine/pageControllers/helpers/state.js'
-import { generateUniqueReference } from '~/src/server/plugins/engine/referenceNumbers.js'
+import { DEFAULT_REFERENCE_NUMBER } from '~/src/server/plugins/engine/referenceNumbers.js'
 import * as defaultServices from '~/src/server/plugins/engine/services/index.js'
 import {
   type AnyFormRequest,
@@ -54,7 +55,7 @@ export async function redirectOrMakeHandler(
     context: FormContext
   ) => ResponseObject | Promise<ResponseObject>
 ) {
-  const { app, params } = request
+  const { app, params, query } = request
   const { model } = app
 
   if (!model) {
@@ -74,7 +75,12 @@ export async function redirectOrMakeHandler(
       )
     }
 
-    const referenceNumber = generateUniqueReference(prefix)
+    const isForce = 'force' in query
+    const { generateReferenceNumber } = getPluginOptions(request.server)
+    const referenceNumber = isForce
+      ? DEFAULT_REFERENCE_NUMBER
+      : await generateReferenceNumber(prefix)
+
     state = await page.mergeState(request, state, {
       $$__referenceNumber: referenceNumber
     })
diff --git a/src/server/plugins/engine/types.ts b/src/server/plugins/engine/types.ts
index 76a96349c..b4eea4b95 100644
--- a/src/server/plugins/engine/types.ts
+++ b/src/server/plugins/engine/types.ts
@@ -483,6 +483,10 @@ export type SaveAndExitHandler = (
 
 export type GetLanguageHandler = (query?: RequestQuery, yar?: Yar) => string
 
+export type GenerateReferenceNumberHandler = (
+  prefix?: string
+) => Promise<string>
+
 export interface ExternalArgs {
   component: ComponentDef
   controller: QuestionPageController
@@ -523,6 +527,7 @@ export interface PluginOptions {
   preparePageEventRequestOptions?: PreparePageEventRequestOptions
   onRequest?: OnRequestCallback
   getLanguage?: GetLanguageHandler
+  generateReferenceNumber?: GenerateReferenceNumberHandler
   baseUrl: string // base URL of the application, protocol and hostname e.g. "https://myapp.com"
   ordnanceSurveyApiKey?: string
   ordnanceSurveyApiSecret?: string
diff --git a/src/typings/hapi/index.d.ts b/src/typings/hapi/index.d.ts
index e61d5c32f..2cecea6f3 100644
--- a/src/typings/hapi/index.d.ts
+++ b/src/typings/hapi/index.d.ts
@@ -11,6 +11,7 @@ import { type FormModel } from '~/src/server/plugins/engine/models/index.js'
 import {
   type AnyFormRequest,
   type FormSubmissionError,
+  type GenerateReferenceNumberHandler,
   type PluginOptions
 } from '~/src/server/plugins/engine/types.ts'
 import { type CacheService } from '~/src/server/services/index.js'
@@ -41,6 +42,7 @@ declare module '@hapi/hapi' {
       getLanguage?: PluginOptions['getLanguage']
       baseUrl: string
       services: PluginOptions['services']
+      generateReferenceNumber: GenerateReferenceNumberHandler
     }
   }
 
diff --git a/test/form/postcode-lookup.test.js b/test/form/postcode-lookup.test.js
index c92de22e2..d05f24373 100644
--- a/test/form/postcode-lookup.test.js
+++ b/test/form/postcode-lookup.test.js
@@ -72,7 +72,8 @@ describe('Postcode lookup form pages', () => {
         getFlash: jest.fn().mockReturnValue(undefined),
         setFlash: jest.fn()
       },
-      saveAndExit: undefined
+      saveAndExit: undefined,
+      generateReferenceNumber: jest.fn().mockReturnValue('XXX-XXX-XXX')
     })
   })