> ## Documentation Index > Fetch the complete documentation index at: https://docs.streamlinedpayments.com/llms.txt > Use this file to discover all available pages before exploring further. # Update invoice > Updates an issued invoice. Every field is optional; only what you send is changed. `billing_milestones_attributes` requires the Scale plan and returns `422` without it. Send `id` to change an existing milestone, omit it to add one, and send `_destroy: true` with an `id` to remove one. ## OpenAPI ````yaml /api-reference/openapi.yaml put /invoices/{id} openapi: 3.0.3 info: title: Streamlined API description: > Access customers, customer applications, customer groups, products, payouts, invoices, transactions, and deposit links programmatically through this API, and receive webhooks when deposit links change. All requests must be authenticated with an API key. version: 1.6.0 license: name: Proprietary url: https://streamlinedpayments.com/terms servers: - url: https://api.staging.streamlinedpayments.com/api/v1 description: Sandbox - url: https://api.streamlinedpayments.com/api/v1 description: Production security: - AppIdAuth: [] ApiKeyAuth: [] tags: - name: Customers description: Create, update and delete the businesses you sell to. - name: Customer applications description: >- List the applications your customers submit, and approve them. Approving can also set net terms and export the customer to Shopify. See [Approve customer applications](/guides/customer-applications). - name: Customer groups description: >- Organize customers into groups and manage who's in each one. A group can be linked to a Shopify B2B company. - name: Customer files description: Upload and manage files attached to a customer. - name: Customer addresses description: Manage a customer's addresses and choose their default billing address. - name: Orders description: Create orders, add and remove line items, and schedule them. - name: Invoices description: Create invoices from orders, then list, look up and update them. - name: Transactions description: List transactions and look one up. - name: Payouts description: List payouts, including pending ones, and look one up. - name: Products description: >- Create and update the products and services you sell, import them in bulk, and merge duplicates. - name: Deposit links description: Collect money from a customer before an invoice exists. - name: Webhooks description: >- Register HTTPS endpoints to receive events when something changes. See [Webhooks](/guides/webhooks) for signatures, retries and delivery guarantees. paths: /invoices/{id}: put: tags: - Invoices summary: Update invoice description: > Updates an issued invoice. Every field is optional; only what you send is changed. `billing_milestones_attributes` requires the Scale plan and returns `422` without it. Send `id` to change an existing milestone, omit it to add one, and send `_destroy: true` with an `id` to remove one. operationId: updateInvoice parameters: - name: id in: path description: The UUID of the invoice to update required: true schema: type: string format: uuid requestBody: required: true content: application/json: schema: type: object properties: due_date: type: string format: date memo: type: string po_number: type: string billing_milestones_attributes: type: array description: Scale plan only. items: type: object properties: id: type: string description: Omit to add a new milestone. name: type: string amount: type: integer description: >- In cents when amount_type is `fixed`, a percentage when `percentage`. amount_type: type: string enum: - fixed - percentage net_terms: type: integer due_date: type: string format: date issued_at: type: string format: date-time issue_method: type: string _destroy: type: boolean description: Send with an `id` to remove that milestone. responses: '200': description: Invoice updated content: application/json: schema: $ref: '#/components/schemas/InvoiceUpdated' '401': $ref: '#/components/responses/Unauthorized' '404': description: Invoice not found content: application/json: schema: $ref: '#/components/schemas/Error' example: error: Invoice not found '422': description: The update was rejected content: application/json: schema: $ref: '#/components/schemas/Error' example: error: Milestone billing is not available on your plan components: schemas: InvoiceUpdated: type: object description: >- Returned by Update Invoice. Narrower than InvoiceDetail, and it carries milestones. properties: invoice: type: object properties: uuid: type: string format: uuid created_at: type: string format: date-time currency: $ref: '#/components/schemas/Currency' amount: type: integer identifier: type: string due_date: type: string format: date status: type: string current_open_balance: type: integer payment_url: type: string recipient: $ref: '#/components/schemas/InvoiceRecipient' billing_milestones: type: array items: $ref: '#/components/schemas/BillingMilestone' Error: type: object properties: error: type: string message: type: string Currency: type: string description: >- ISO currency code. Most resources support these. Products are limited to USD, CAD, EUR, GBP, AUD. enum: - USD - CAD - GBP - EUR - AUD - JPY - INR InvoiceRecipient: type: object properties: uuid: type: string format: uuid company_name: type: string nullable: true display_name: type: string nullable: true description: >- Company name if present, otherwise first/last name. Null if neither is set. BillingMilestone: type: object properties: uuid: type: string name: type: string amount: type: integer amount_type: type: string enum: - fixed - percentage due_date: type: string format: date has_been_issued: type: boolean current_open_balance: type: integer responses: Unauthorized: description: Authentication failed content: application/json: schema: $ref: '#/components/schemas/Error' examples: AuthenticationRequired: value: error: Authentication required message: >- API endpoint requires authentication. Please provide valid X-App-Id and X-Api-Key headers. InvalidCredentials: value: error: Invalid credentials message: >- The provided API credentials are invalid. Please check your X-App-Id and X-Api-Key values. securitySchemes: AppIdAuth: type: apiKey in: header name: X-App-Id description: App ID for authentication ApiKeyAuth: type: apiKey in: header name: X-Api-Key description: API Key for authentication ```` This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.