> ## Documentation Index > Fetch the complete documentation index at: https://developer.fin.com/llms.txt > Use this file to discover all available pages before exploring further. # Attach Documents to Business Customer > Attach formation, ownership, and supporting documents to an existing business customer. Documents are categorised into three arrays: formation_documents, ownership_documents, and supporting_documents. * Upload files first using the [Upload document](https://developer.fin.com/api-reference/customers/upload-document) endpoint to obtain URIs, then reference them here. * Parse `tos_policies_value` from the `tos_policies_url` returned by `POST /v2/customers/business` and include it in this request. * Maximum file size is 5 MB per file. ## Document Type Reference See [Entity-wise document requirement](https://developer.fin.com/guides/customers-and-compliance/entity-wise-document-requirement) for all valid `type` values per category and entity type. ## OpenAPI ````yaml POST /v2/customers/{customer_id}/business/attach openapi: 3.1.0 info: title: Fin.com API version: 1.0.0 description: >- A simple API specification for Fin.com, a financial services platform that provides a range of banking and payment solutions for businesses and individuals. This API allows developers to integrate Fin.com's services into their applications, enabling functionalities such as customer management, transaction processing, and access to financial data. servers: - url: https://sandbox.api.fin.com description: Sandbox server - url: https://api.fin.com description: Production server security: [] tags: - name: Authentication description: A modified OAuth 2.0 Client Credential Flow - name: Customers description: Customer management and document upload operations - name: Balances description: Retrieve wallet balance information - name: Catalogue description: | A set of endpoints to retrieve contextual data to assemble requests to fin.com's API - name: Beneficiaries description: Manage beneficiary accounts for payments and transfers - name: Transactions description: Transaction history and management for beneficiaries - name: Virtual Accounts description: Create and manage virtual accounts for USD to USDC conversions - name: Fees & FX Rates description: Retrieve fees and foreign exchange rates - name: Crypto Orchestration description: >- Accept crypto deposits from exchange and external wallets and settle them to a destination wallet paths: /v2/customers/{customer_id}/business/attach: post: tags: - Customers summary: Attach Documents to Business Customer description: >- Attach formation, ownership, and supporting documents to an existing business customer. Documents are categorised into three arrays: formation_documents, ownership_documents, and supporting_documents. parameters: - name: customer_id in: path required: true schema: type: string format: uuid description: Unique identifier for the business customer example: ed54db74-7dbe-47d2-8ea0-c2bf2a9dda06 requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/AttachDocumentsToBusinessCustomerV2Input' example: formation_documents: - type: EVIDENCE_OF_DIRECTORS_AND_CONTROLLERS description: Certificate of Incorporation files: - uri: /AbAcQ4hn_0652746727637.pdf - type: REGISTRATION_DOCUMENT description: Business registration doc files: - uri: /AbAcQ4hn_0652746727638.pdf ownership_documents: - type: PROOF_OF_SIGNATORY_AUTHORITY description: Shareholder Registry files: - uri: /XyZ123mn_0652746727639.pdf supporting_documents: - type: PROOF_OF_SOURCE_OF_FUNDS files: - uri: /PoAdef45_0652746727640.pdf - type: PROOF_OF_ADDRESS files: - uri: /PoAdef45_0652746727641.pdf tos_policies_value: 6955e70b-f9f3-4076-b1ce-5c897085dd24 responses: '200': description: Documents attached successfully content: application/json: schema: type: object properties: data: type: object description: Generic response object '400': description: Validation failed content: application/json: schema: type: object properties: status: type: integer example: 400 message: type: string example: Validation failed data: type: object additionalProperties: type: string '401': $ref: '#/components/responses/AuthenticationError' '404': $ref: '#/components/responses/NotFoundError' '422': $ref: '#/components/responses/ValidationError' security: - bearerAuth: [] components: schemas: AttachDocumentsToBusinessCustomerV2Input: type: object required: - tos_policies_value properties: formation_documents: type: array description: >- Documents proving the legal existence of the business (e.g., Certificate of Incorporation, Articles of Incorporation, Tax registration certificate). items: $ref: '#/components/schemas/V2FormationDocumentItem' ownership_documents: type: array description: >- Documents proving who controls and owns the business (e.g., Shareholder Register, Org Chart, Power of Attorney, Directors Registry). items: $ref: '#/components/schemas/V2OwnershipDocumentItem' supporting_documents: type: array description: >- Additional compliance and operational documents (e.g., Proof of Address, Proof of Source of Funds, AML Comfort Letter, Marketing Materials). items: $ref: '#/components/schemas/V2SupportingDocumentItem' tos_policies_value: type: string description: >- Parsed from the tos_policies_value query parameter in the tos_policies_url returned by POST /v2/customers/business. Signifies the customer has accepted the Terms of Service. example: f11e77c6-8dc0-4d4b-a3f2-ed84c8ccfc69 V2FormationDocumentItem: type: object required: - files properties: type: type: string enum: - REGISTRATION_DOCUMENT - CONSTITUTIONAL_DOCUMENT - FORMATION_DOCUMENT - PROOF_OF_TAX_IDENTIFICATION - EVIDENCE_OF_DIRECTORS_AND_CONTROLLERS description: Formation document type. example: REGISTRATION_DOCUMENT description: type: string description: Optional human-readable description of this specific document. example: Certificate of Incorporation files: type: array description: >- One or more file URIs obtained from [Upload Document](https://developer.fin.com/api-reference/customers/upload-document) endpoint. minItems: 1 items: type: object required: - uri properties: uri: type: string description: File URI returned by the upload endpoint. example: /AbAcQ4hn_0652746727639.pdf V2OwnershipDocumentItem: type: object required: - files properties: type: type: string enum: - OWNERSHIP_INFORMATION - OWNERSHIP_CHART - PROOF_OF_SIGNATORY_AUTHORITY description: Ownership document type. example: OWNERSHIP_INFORMATION description: type: string description: Optional human-readable description of this specific document. example: Ownership information document files: type: array description: >- One or more file URIs obtained from [Upload Document](https://developer.fin.com/api-reference/customers/upload-document) endpoint. minItems: 1 items: type: object required: - uri properties: uri: type: string description: File URI returned by the upload endpoint. example: /AbAcQ4hn_0652746727639.pdf V2SupportingDocumentItem: type: object required: - files properties: type: type: string enum: - SHAREHOLDER_REGISTER - PROOF_OF_NATURE_OF_BUSINESS - PROOF_OF_ENTITY_NAME_CHANGE - CERT_OF_INCUMBENCY - PROOF_OF_SOURCE_OF_FUNDS - PROOF_OF_SOURCE_OF_WEALTH - AML_COMFORT_LETTER - MARKETING_MATERIALS - TAX_EXEMPT_ENTITY_CONFIRMATION - E_SIGNATURE_CERTIFICATE - FLOW_OF_FUNDS - PROOF_OF_NATURE_OF_BUSINESS_LICENSE - PROOF_OF_NATURE_OF_BUSINESS_AML_POLICY - EVIDENCE_OF_GOOD_STANDING - PROOF_OF_ACCOUNT_PURPOSE - PROOF_OF_ADDRESS - OTHER description: Supporting document type. example: PROOF_OF_SOURCE_OF_FUNDS description: type: string description: Optional human-readable description of this specific document. example: Bank statements for the past 6 months files: type: array description: >- One or more file URIs obtained from [Upload Document](https://developer.fin.com/api-reference/customers/upload-document) endpoint. minItems: 1 items: type: object required: - uri properties: uri: type: string description: File URI returned by the upload endpoint. example: /AbAcQ4hn_0652746727639.pdf responses: AuthenticationError: description: Authentication failed due to invalid credentials content: application/json: schema: type: object properties: message: type: string example: Authentication failed NotFoundError: description: Resource not found content: application/json: schema: type: object properties: message: type: string example: Resource not found ValidationError: description: Failed due to a formatting error. content: application/json: schema: type: object required: - message properties: message: type: string errors: type: array items: type: object additionalProperties: type: string securitySchemes: bearerAuth: type: http scheme: bearer bearerFormat: JWT description: >- Bearer token authentication. Obtain token from [Issue a Token](https://developer.fin.com/api-reference/authentication/issue-a-token) endpoint ```` This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.