diff --git a/src/config/index.ts b/src/config/index.ts
index b2341f273..5404edd27 100644
--- a/src/config/index.ts
+++ b/src/config/index.ts
@@ -111,7 +111,7 @@ export const config = convict({
    */
   sessionTimeout: {
     format: Number,
-    default: oneHour * 24, // 1 day
+    default: oneHour * 168, // 7 days
     env: 'SESSION_TIMEOUT'
   },
   confirmationSessionTimeout: {
diff --git a/src/server/plugins/engine/pageControllers/QuestionPageController.ts b/src/server/plugins/engine/pageControllers/QuestionPageController.ts
index 7b6646b7a..7614afbd5 100644
--- a/src/server/plugins/engine/pageControllers/QuestionPageController.ts
+++ b/src/server/plugins/engine/pageControllers/QuestionPageController.ts
@@ -21,7 +21,11 @@ import {
 } from '~/src/server/plugins/engine/helpers.js'
 import { type FormModel } from '~/src/server/plugins/engine/models/index.js'
 import { PageController } from '~/src/server/plugins/engine/pageControllers/PageController.js'
+import { extendFileRetention } from '~/src/server/plugins/engine/services/formSubmissionService.js'
+import { type FilePersistData } from '~/src/server/plugins/engine/services/types.js'
 import {
+  FileStatus,
+  type FileState,
   type FormContext,
   type FormContextRequest,
   type FormPageViewModel,
@@ -321,7 +325,45 @@ export class QuestionPageController extends PageController {
     }
 
     const { cacheService } = request.services([])
-    return cacheService.setState(request, updated)
+    const newState = await cacheService.setState(request, updated)
+
+    await this.updateFileRetention(newState)
+
+    return newState
+  }
+
+  /**
+   * Checks the updated session state for any file upload information and,
+   * if found, calls the file retention service to extend the files' S3 expiration.
+   * @param state - The current session state.
+   */
+  private async updateFileRetention(state: FormSubmissionState): Promise<void> {
+    if (!state.upload) {
+      return
+    }
+
+    const files: FilePersistData[] = []
+
+    const uploads = state.upload ?? {}
+    Object.keys(uploads).forEach((uploadKey) => {
+      const uploadData = uploads[uploadKey]
+      if (Array.isArray(uploadData.files) && uploadData.files.length > 0) {
+        uploadData.files.forEach((file: FileState) => {
+          // Only extend retention if the file upload is complete otherwise we'll run into a race condition.
+          if (file.status.form.file.fileStatus === FileStatus.complete) {
+            files.push({
+              fileId: file.status.form.file.fileId
+            })
+          }
+        })
+      }
+    })
+
+    if (files.length > 0) {
+      const retrievalKey =
+        this.model.def.outputEmail ?? 'defraforms@defra.gov.uk'
+      await extendFileRetention(files, retrievalKey)
+    }
   }
 
   makeGetRouteHandler() {
diff --git a/src/server/plugins/engine/services/formSubmissionService.js b/src/server/plugins/engine/services/formSubmissionService.js
index 2da62b399..cb73d0afa 100644
--- a/src/server/plugins/engine/services/formSubmissionService.js
+++ b/src/server/plugins/engine/services/formSubmissionService.js
@@ -1,19 +1,19 @@
 import { config } from '~/src/config/index.js'
 import { postJson } from '~/src/server/services/httpService.js'
-
 const submissionUrl = config.get('submissionUrl')
 
 /**
  * Persist files by extending the time-to-live to 30 days
- * @param {{fileId: string, initiatedRetrievalKey: string}[]} files - batch of files to persist
- * @param {string} persistedRetrievalKey - final retrieval key when submitting
+ * @param {FilePersistData[]} files Files to persist.
+ * @param {string} retrievalKey Final retrieval key when submitting (usually the output email).
+ * @returns {Promise<object>} The result payload.
  */
-export async function persistFiles(files, persistedRetrievalKey) {
+export async function persistFiles(files, retrievalKey) {
   const postJsonByType = /** @type {typeof postJson<object>} */ (postJson)
 
   const payload = {
-    files,
-    persistedRetrievalKey
+    retrievalKey,
+    files
   }
 
   const result = await postJsonByType(`${submissionUrl}/files/persist`, {
@@ -23,6 +23,21 @@ export async function persistFiles(files, persistedRetrievalKey) {
   return result
 }
 
+/**
+ * Extend the retention time for uploaded files.
+ * @param {FilePersistData[]} files Array of file objects.
+ * @param {string} retrievalKey The key (usually the user's email) to be used for persistence.
+ * @returns {Promise<object>} The result payload.
+ */
+export async function extendFileRetention(files, retrievalKey) {
+  const payload = {
+    retrievalKey,
+    files
+  }
+  const result = await postJson(`${submissionUrl}/file/extend`, { payload })
+  return result
+}
+
 /**
  * Submit form
  * @param {SubmitPayload} data - submission data
@@ -44,3 +59,7 @@ export async function submit(data) {
 /**
  * @import { SubmitPayload, SubmitResponsePayload } from '@defra/forms-model'
  */
+
+/**
+ * @import { FilePersistData } from '~/src/server/plugins/engine/services/types.js'
+ */
diff --git a/src/server/plugins/engine/services/types.js b/src/server/plugins/engine/services/types.js
new file mode 100644
index 000000000..e1908be14
--- /dev/null
+++ b/src/server/plugins/engine/services/types.js
@@ -0,0 +1,5 @@
+/**
+ * @typedef {object} FilePersistData
+ * @property {string} fileId The unique identifier for the file.
+ * @property {string} [initiatedRetrievalKey] The retrieval key that was assigned when the file was initiated.
+ */
diff --git a/src/server/plugins/session.ts b/src/server/plugins/session.ts
index e94e42fe9..125be322c 100644
--- a/src/server/plugins/session.ts
+++ b/src/server/plugins/session.ts
@@ -22,7 +22,8 @@ export default {
     // storeBlank: false,
     cookieOptions: {
       password: config.get('sessionCookiePassword'),
-      isSecure: config.get('isProduction')
+      isSecure: config.get('isProduction'),
+      ttl: 7 * 24 * 60 * 60 * 1000 // 7 days
     }
   }
 } satisfies ServerRegisterPluginObject<YarOptions>
diff --git a/src/server/types.ts b/src/server/types.ts
index e94b876a8..663389e88 100644
--- a/src/server/types.ts
+++ b/src/server/types.ts
@@ -7,6 +7,7 @@ import {
 
 import { type FormModel } from '~/src/server/plugins/engine/models/index.js'
 import { type DetailItem } from '~/src/server/plugins/engine/models/types.js'
+import { type FilePersistData } from '~/src/server/plugins/engine/services/types.js'
 import {
   type FormRequestPayload,
   type FormStatus
@@ -22,7 +23,7 @@ export interface FormsService {
 
 export interface FormSubmissionService {
   persistFiles: (
-    files: { fileId: string; initiatedRetrievalKey: string }[],
+    files: FilePersistData[],
     persistedRetrievalKey: string
   ) => Promise<object>
   submit: (data: SubmitPayload) => Promise<SubmitResponsePayload | undefined>
diff --git a/src/server/views/help/cookies.html b/src/server/views/help/cookies.html
index 3bad81816..7b93dbc62 100644
--- a/src/server/views/help/cookies.html
+++ b/src/server/views/help/cookies.html
@@ -30,7 +30,7 @@ <h2 class="govuk-heading-m">Essential cookies</h2>
         [
           { text: "session" },
           { text: "Remembers the information you enter" },
-          { text: "When you close the browser, or after 24 hours" }
+          { text: "When you close the browser, or after 7 days" }
         ],
         [
           { text: "crumb" },