> ## Documentation Index > Fetch the complete documentation index at: https://perfgrid.com/docs/llms.txt > Use this file to discover all available pages before exploring further. # Apply credit to an invoice > Puts the credit balance on an open proforma in the same currency, as much as its amount before VAT allows; VAT is worked out on what is left. Credit can't be taken off an invoice this way. A proforma the credit covers in full is paid at once. Needs `billing.pay`. The answer is the whole invoice for a token that also has `billing.view`, and otherwise its `id`, `type`, `status`, `currency`, `credit` and `amount_due`. ## OpenAPI ````yaml /api-reference/console/openapi.json post /invoices/{invoice}/credit openapi: 3.1.2 info: title: PerfGrid API version: 1.0.0 description: >- The PerfGrid customer API. A member creates a token for one billing account under *API tokens* in the panel; it can do what both the token's permissions and the member's own permissions allow, the same as the panel. Send it as `Authorization: Bearer pgapi_...`. Each token may make 120 requests a minute, of which 30 change something; a `429` response says when to try again (`Retry-After`). Ids are the ULIDs the API returns; amounts are decimal strings next to their currency; lists are newest first and paged with `cursor` (`meta.next_cursor`). Messages are in English, or Danish with `Accept-Language: da`. The same tokens work with the MCP server at `/mcp` for AI assistants. servers: - url: https://console.perfgrid.com/api/v1 security: - http: [] tags: - name: Account - name: Invoices - name: Services - name: Domains - name: Support paths: /invoices/{invoice}/credit: post: tags: - Invoices summary: Apply credit to an invoice description: |- Puts the credit balance on an open proforma in the same currency, as much as its amount before VAT allows; VAT is worked out on what is left. Credit can't be taken off an invoice this way. A proforma the credit covers in full is paid at once. Needs `billing.pay`. The answer is the whole invoice for a token that also has `billing.view`, and otherwise its `id`, `type`, `status`, `currency`, `credit` and `amount_due`. operationId: v1.invoices.credit parameters: - name: invoice in: path required: true schema: type: string responses: '200': description: '`InvoiceResource`' content: application/json: schema: anyOf: - type: object properties: data: type: object properties: id: type: string type: type: string enum: - invoice - proforma status: type: string enum: - unpaid - paid - canceled - held currency: type: string credit: type: string amount_due: type: string required: - id - type - status - currency - credit - amount_due required: - data - type: object properties: data: allOf: - $ref: '#/components/schemas/InvoiceResource' - type: object required: - lines - tax_totals - payments - credit_notes required: - data '403': $ref: '#/components/responses/AuthorizationException' components: schemas: InvoiceResource: type: object properties: id: type: string type: type: string enum: - invoice - proforma status: type: string enum: - unpaid - paid - canceled - held is_overdue: type: boolean reference: type: string number: type: - string - 'null' proforma_number: type: string currency: type: string net: type: - string - 'null' credit: type: - string - 'null' subtotal: type: - string - 'null' tax: type: - string - 'null' total: type: - string - 'null' paid: type: - string - 'null' amount_due: type: - string - 'null' payment_in_progress: type: boolean issue_date: type: - string - 'null' due_date: type: - string - 'null' tax_point_date: type: - string - 'null' paid_at: type: - string - 'null' canceled_at: type: - string - 'null' eur: type: - object - 'null' properties: rate: type: - string - 'null' rate_date: type: - string - 'null' subtotal: type: - string - 'null' tax: type: - string - 'null' total: type: - string - 'null' required: - rate - rate_date - subtotal - tax - total notes: type: - string - 'null' lines: type: array items: type: object properties: description: type: string details: type: - string - 'null' period_start: type: - string - 'null' period_end: type: - string - 'null' quantity: type: string unit_price: type: - string - 'null' discount: type: - string - 'null' net: type: - string - 'null' tax_scheme: type: string enum: - domestic - oss - reverse_charge - outside_eu tax_country: type: - string - 'null' tax_rate: type: string required: - description - details - period_start - period_end - quantity - unit_price - discount - net - tax_scheme - tax_country - tax_rate tax_totals: type: array items: type: object properties: tax_scheme: type: string enum: - domestic - oss - reverse_charge - outside_eu tax_country: type: - string - 'null' tax_rate: type: string taxable: type: - string - 'null' tax: type: - string - 'null' required: - tax_scheme - tax_country - tax_rate - taxable - tax payments: type: array items: type: object properties: id: type: string method: type: string enum: - bank_transfer - card - ideal - other amount: type: - string - 'null' paid_at: type: - string - 'null' required: - id - method - amount - paid_at credit_notes: type: array items: type: object properties: id: type: string number: type: string total: type: - string - 'null' issue_date: type: - string - 'null' required: - id - number - total - issue_date links: type: object properties: pdf: type: string required: - pdf required: - id - type - status - is_overdue - reference - number - proforma_number - currency - net - credit - subtotal - tax - total - paid - amount_due - payment_in_progress - issue_date - due_date - tax_point_date - paid_at - canceled_at - eur - notes - links title: InvoiceResource responses: AuthorizationException: description: Authorization error content: application/json: schema: type: object properties: message: type: string description: Error overview. required: - message securitySchemes: http: type: http description: >- An API token from *API tokens* in the console, sent as `Authorization: Bearer pgapi_...`. It works for one billing account, and its permissions decide which endpoints it may call. scheme: bearer ```` This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.