> ## Documentation Index > Fetch the complete documentation index at: https://docs.codaclean.io/llms.txt > Use this file to discover all available pages before exploring further. # Créer un client > Creates a customer. All fields are required except `address.street2`, `bankAccounts` and `payrollProviders`. Bank accounts and payroll providers can be included now or added later. Mandate signature requests are sent to the `contact`. Any field outside the documented ones is rejected with `unknownField`. An enterprise number can belong to only one accounting firm. If another firm already registered it, the call returns `403 belongsToAnotherTenant`. In that case, the accountant must contact Codaclean support to start a transfer procedure, which requires the end customer's agreement. **Required scope:** `customers:write` ## OpenAPI ````yaml POST /customers/new openapi: 3.1.0 info: title: Codaclean API version: '1.0' description: > The Codaclean external API lets partner software (accounting tools, practice management software, sync agents) integrate with Codaclean on behalf of an accounting firm: manage its customers, request CODA and CODB mandates, and retrieve the CODA and CODB files Codaclean receives for them. servers: - url: https://api.codaclean.io/v1 description: Production - url: https://api.test.codaclean.io/v1 description: Staging security: - apiKeyAuth: [] bearerAuth: [] tags: - name: Authentication description: Obtain and refresh the ID token sent with every other call. - name: Utilities description: Connectivity check. - name: Customers description: The customers (client companies) managed by the accounting firm. - name: Bank accounts description: Bank accounts (IBANs) linked to a customer. - name: Customer payroll providers description: Payroll providers (social secretariats) linked to a customer. - name: Mandates description: CODA mandates (per bank account) and CODB mandates (per payroll provider). - name: Reference data description: Banks and payroll providers known to Codaclean. - name: CODA files description: Bank statement files in CODA format. - name: CODB files description: Payroll files in CODB format, delivered by payroll providers. paths: /customers/new: post: tags: - Customers summary: Create a customer description: > Creates a customer. All fields are required except `address.street2`, `bankAccounts` and `payrollProviders`. Bank accounts and payroll providers can be included now or added later. Mandate signature requests are sent to the `contact`. Any field outside the documented ones is rejected with `unknownField`. An enterprise number can belong to only one accounting firm. If another firm already registered it, the call returns `403 belongsToAnotherTenant`. In that case, the accountant must contact Codaclean support to start a transfer procedure, which requires the end customer's agreement. **Required scope:** `customers:write` operationId: createCustomer requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/CustomerCreate' examples: customer: summary: New customer value: enterpriseNumber: 0159.145.821 name: Atelier Martin SRL accountingRef: MARTIN address: street: Place du Jeu de Balle 3 zipCode: '1000' municipality: Bruxelles country: Belgique contact: name: Sophie Martin function: Manager email: accounting@example.com language: fr responses: '201': description: Customer created. content: application/json: schema: $ref: '#/components/schemas/Customer' examples: created: summary: Customer created value: id: 6ab7bba70d0379c741b7f74c enterpriseNumber: 0159.145.821 name: Atelier Martin SRL accountingRef: MARTIN address: street: Place du Jeu de Balle 3 zipCode: '1000' municipality: Bruxelles country: Belgique contact: name: Sophie Martin function: Manager email: accounting@example.com language: fr isConfidential: false bankAccounts: [] payrollProviders: [] createdOn: '2026-09-26T12:33:43.783Z' '400': description: >- `invalidPayload`, `unknownField`, `invalidEnterpriseNumber` or `invalidIban`. content: application/json: schema: $ref: '#/components/schemas/Error' examples: unknownField: summary: Field not accepted value: message: 'Unknown field(s): isConfidential' code: unknownField fields: - isConfidential invalidEnterpriseNumber: summary: Invalid enterprise number value: message: Enterprise number 0000000000 is not valid code: invalidEnterpriseNumber '401': $ref: '#/components/responses/Unauthorized' '403': description: >- `forbiddenScope`, or `belongsToAnotherTenant` — the enterprise number or an IBAN is already used by another accounting firm. content: application/json: schema: $ref: '#/components/schemas/Error' examples: belongsToAnotherTenant: summary: Registered by another accounting firm value: message: Customer 0184.574.865 already exists code: belongsToAnotherTenant noApiKey: summary: No API key value: message: Forbidden invalidApiKey: summary: Invalid API key value: message: Forbidden '404': description: '`payrollProviderNotFound` — unknown payroll provider code.' content: application/json: schema: $ref: '#/components/schemas/Error' examples: payrollProviderNotFound: summary: Unknown payroll provider code value: message: Payroll provider UNKNOWN not found code: payrollProviderNotFound '409': description: >- `customerAlreadyExists` or `ibanAlreadyInUse` — already registered in your accounting firm. content: application/json: schema: $ref: '#/components/schemas/Error' examples: customerAlreadyExists: summary: Already registered value: message: Customer 0159.145.821 already exists code: customerAlreadyExists '429': $ref: '#/components/responses/TooManyRequests' '500': $ref: '#/components/responses/InternalError' components: schemas: CustomerCreate: type: object required: - enterpriseNumber - name - accountingRef - address - contact additionalProperties: false properties: enterpriseNumber: type: string pattern: ^[01]\d{3}\.\d{3}\.\d{3}$ description: > Belgian enterprise number, formatted `0123.456.789`: 10 digits with dots, without the `BE` prefix. Its check digits are validated, and it must be unique across Codaclean. name: type: string description: Non-empty. accountingRef: type: string description: Your internal reference for the customer. address: description: All fields are required except `street2`. allOf: - $ref: '#/components/schemas/Address' - required: - street - zipCode - municipality - country contact: description: >- All fields are required. Mandate signature requests are sent to this contact. allOf: - $ref: '#/components/schemas/Contact' - required: - name - function - email - language bankAccounts: type: array description: Only `iban` is accepted. BIC and bank name are derived by Codaclean. items: type: object required: - iban additionalProperties: false properties: iban: type: string payrollProviders: type: array description: Only `code` is accepted. See `POST /payroll-providers`. items: type: object required: - code additionalProperties: false properties: code: type: string Customer: type: object description: >- Fields without a value are omitted from the response. Arrays are always present. properties: id: type: string enterpriseNumber: type: string description: Belgian enterprise number, formatted `0123.456.789`. name: type: string accountingRef: type: string address: $ref: '#/components/schemas/Address' contact: $ref: '#/components/schemas/Contact' isConfidential: type: boolean description: >- Confidential customers are only visible to users with the Administrator access level. bankAccounts: type: array description: Active bank accounts only. items: $ref: '#/components/schemas/BankAccount' payrollProviders: type: array description: Active payroll providers only. items: $ref: '#/components/schemas/CustomerPayrollProvider' createdOn: type: string format: date-time updatedOn: type: string format: date-time Error: type: object description: > Error body. `code` is a stable, machine-readable token; it is present on errors returned by the customers, mandates and reference-data endpoints. Some errors carry extra keys, such as `fields` or `candidates`. required: - message properties: message: type: string description: Human-readable description. Do not parse it. code: type: string description: | Machine-readable error code. **See also:** [Errors](/api/errors#error-codes) fields: type: array items: type: string description: >- Offending fields. Present with `unknownField` and `fieldNotUpdatable`. candidates: type: array description: Present with `connectorSelectionRequired`. items: $ref: '#/components/schemas/ConnectorCandidate' Address: type: object additionalProperties: false properties: street: type: string street2: type: string zipCode: type: string municipality: type: string country: type: string Contact: type: object additionalProperties: false description: >- Contact person at the customer. Mandate signature requests are sent to this contact. properties: name: type: string description: Name of the person who signs the mandates. function: type: string email: type: string description: Email address the mandate signature requests are sent to. language: type: string description: >- Language of the contact: `fr`, `nl` or `en`. Used for the mandate documents and emails. BankAccount: type: object properties: iban: type: string currency: type: string description: >- Always `EUR` unless another value is stored. Output only; not accepted as input. bic: type: string description: >- Derived from the IBAN by Codaclean. Formatted with spaces, for example `GEBA BE BB`. bankName: type: string connectorId: type: integer description: >- Present when the bank account is served through a CODAlight connector. CustomerPayrollProvider: type: object properties: code: type: string description: >- Payroll provider code. `***other***` means another payroll provider, not handled by Codaclean. nameFr: type: string nameNl: type: string ConnectorCandidate: type: object properties: connectorId: type: integer name: type: string bicCode: type: string available: type: boolean Message: type: object description: Confirmation returned by actions that do not return a resource. required: - message properties: message: type: string responses: Unauthorized: description: >- Missing, invalid or expired ID token, or user not allowed to use the API. content: application/json: schema: $ref: '#/components/schemas/Message' examples: noToken: summary: No ID token value: message: Unauthorized invalidToken: summary: Invalid or expired ID token value: message: Unauthorized TooManyRequests: description: Rate limit or quota exceeded for this API key. content: application/json: schema: $ref: '#/components/schemas/Message' examples: tooManyRequests: summary: Rate limit exceeded value: message: Too Many Requests InternalError: description: Unexpected server error. content: application/json: schema: $ref: '#/components/schemas/Error' examples: internalError: summary: Unexpected server error value: message: Internal server error securitySchemes: apiKeyAuth: type: apiKey in: header name: x-api-key description: >- Identifies the partner software. Issued by Codaclean. Required on every call, including `POST /token`. bearerAuth: type: http scheme: bearer bearerFormat: JWT (Cognito ID token) description: >- Identifies the user and their accounting firm. Send the `idToken` returned by `POST /token` as `Authorization: Bearer `. Valid for 1 hour. ````