> ## Documentation Index > Fetch the complete documentation index at: https://docs.flowpayroll.ai/llms.txt > Use this file to discover all available pages before exploring further. # Trigger send HMRC RTI FPS for payroll run > Triggers the sending of HMRC RTI FPS (Full Payment Submission) for a specific payroll run ## OpenAPI ````yaml /api-reference/specs/pay-api.yaml post /rti/fps/{payrollConfigId}/{taxYear}/{period} openapi: 3.0.3 info: title: FlowPayroll API description: >- API for payroll management, including payroll upload, lock, HMRC submission, employee management version: 0.1.0 servers: - url: https://api.sandbox.flowpayroll.ai/v1 security: - XAuthToken: [] XOrgId: [] tags: - name: Employees description: >- Create, retrieve, update, and delete employee records, and look them up by NI number or payroll ID. - name: Starters & leavers description: Set and clear starter and leaver details, individually or in bulk. - name: Tax codes description: >- Manage employee tax codes and query the effective tax code and NI category on a given date. - name: NI & identifiers description: Manage NI categories, National Insurance numbers, and payroll IDs. - name: Student loans description: Start and end student and postgraduate loans. - name: Payroll setup description: Assign an employee's payroll config and set opening balances. - name: Payroll - name: Payroll lines - name: PayrollConfig - name: Pay Elements - name: Calculator - name: Payslip - name: RTI - name: YearEnd - name: Organisation paths: /rti/fps/{payrollConfigId}/{taxYear}/{period}: post: tags: - RTI summary: Trigger send HMRC RTI FPS for payroll run description: >- Triggers the sending of HMRC RTI FPS (Full Payment Submission) for a specific payroll run operationId: triggerSendHmrcRtiFpsForPayrollRun parameters: - name: payrollConfigId in: path required: true schema: type: string pattern: ^[a-zA-Z0-9_-]+$ description: The payroll configuration ID - name: taxYear in: path required: true schema: type: string pattern: ^[0-9]{4}$ description: The tax year - name: period in: path required: true schema: type: string pattern: ^[0-9]+$ description: The payroll period - name: preview in: query required: false schema: type: boolean default: false description: Whether to generate a preview without submitting to HMRC requestBody: required: false content: application/json: schema: type: string description: Final submission details (required for last period of tax year) example: Final submission details for the period responses: '200': description: HMRC RTI FPS preview generated successfully content: application/json: schema: allOf: - $ref: '#/components/schemas/ResponseBody' - type: object properties: data: type: string description: The FPS submission XML preview example: ... '202': description: FPS submission triggered successfully content: application/json: schema: $ref: '#/components/schemas/ResponseBody' '400': description: >- Invalid request, payroll run not completed, or final submission details required content: application/json: schema: allOf: - $ref: '#/components/schemas/ResponseBody' - type: object properties: data: $ref: '#/components/schemas/FinalSubmissionErrorResponseDto' '404': description: Payroll config, payroll run, or HMRC settings not found content: application/json: schema: $ref: '#/components/schemas/ResponseBody' '409': description: Payroll run already submitted to HMRC content: application/json: schema: $ref: '#/components/schemas/ResponseBody' '500': description: Internal server error content: application/json: schema: $ref: '#/components/schemas/ResponseBody' components: schemas: ResponseBody: type: object properties: message: $ref: '#/components/schemas/MessageWithTokenResponse' content: type: object properties: data: type: object nullable: true metadata: type: object nullable: true properties: dateFormat: type: string default: yyyy-MM-dd dateTimeFormat: type: string default: yyyy-MM-ddTHH:mm:ss.fffZ paginationToken: type: string nullable: true validationIssues: type: array items: $ref: '#/components/schemas/ValidationIssue' messageToken: type: string FinalSubmissionErrorResponseDto: type: object properties: example: type: object description: Example of the required final submission details format example: field1: value1 field2: value2 description: type: string description: Description of what final submission details are required example: >- Final submission details are required for the last period of the tax year 2025-2026. Please provide the details in the request body using the example format above. type: type: string description: The type of final submission details required example: FinalSubmissionDetailsY2025To26 taxYear: type: string description: The tax year range example: 2025-2026 required: - example - description - type - taxYear MessageWithTokenResponse: type: object properties: text: type: string token: type: string tokenArguments: type: array items: $ref: '#/components/schemas/ValidationIssueArgument' ValidationIssue: type: object description: > Field validation item. `reasonToken` is a stable snake_case key for i18n or custom client messages; `reason` is the default English text from the API. properties: field: type: string description: Dot-path of the field (e.g. name.firstName, address.line1). reason: type: string description: Default human-readable message. reasonToken: type: string description: Machine-readable error identifier (snake_case). reasonTokenArguments: type: array nullable: true items: $ref: '#/components/schemas/ValidationIssueArgument' ValidationIssueArgument: type: object properties: name: type: string value: type: string securitySchemes: XAuthToken: type: apiKey in: header name: X-Auth-Token description: Access token obtained from OAuth2 client credentials flow XOrgId: type: apiKey in: header name: X-Org-Id description: >- Organisation to scope the request to. Required when the principal can access more than one organisation; optional for single-organisation principals (the authorizer resolves it automatically). ````