> ## Documentation Index > Fetch the complete documentation index at: https://docs.useaira.com/llms.txt > Use this file to discover all available pages before exploring further. # Create invoice line item > Creates a line item on a one-off invoice, optionally with sub-line items. When sub-line items are provided, their amounts must sum to the line item amount. ## OpenAPI ````yaml /api-reference/openapi.yaml post /v1/invoices/{invoiceId}/line-items openapi: 3.1.0 info: title: API Reference version: '1.0' description: Aira API Reference x-logo: url: https://static.useaira.com/images/airalogo.svg backgroundColor: '#FFFFFF' altText: Aira Logo servers: - url: https://api.useaira.com description: API base URL security: - ApiKey: [] paths: /v1/invoices/{invoiceId}/line-items: post: tags: - Invoices summary: Create invoice line item description: >- Creates a line item on a one-off invoice, optionally with sub-line items. When sub-line items are provided, their amounts must sum to the line item amount. parameters: - schema: type: string format: uuid in: path name: invoiceId required: true requestBody: content: application/json: schema: type: object properties: idempotencyKey: type: string minLength: 1 pattern: ^[a-zA-Z0-9_-]+$ description: >- A unique idempotency key for this line item, scoped to the invoice. productId: type: string format: uuid itemId: type: string format: uuid name: type: string nullable: true description: >- Optional line item name; defaults to the item name (or product name as fallback) when null. startDate: type: string format: date endDate: type: string format: date lineItemGroupId: type: string format: uuid nullable: true description: >- Optional line item group to attach this line item to. The group must belong to the same invoice. amount: type: number subLineItems: type: array description: >- Optional breakdown of the line item amount into sub-line items. When provided, amounts must sum to amount. items: type: object properties: usage: type: number amount: type: number required: - usage - amount additionalProperties: false default: [] required: - idempotencyKey - productId - itemId - startDate - endDate - amount additionalProperties: false required: true description: >- Schema for creating a one-off line item on an existing one-off invoice. When subLineItems is provided, the sum of subLineItems.amount must equal amount. responses: '200': description: Default Response content: application/json: schema: type: object properties: id: type: string format: uuid idempotencyKey: type: string customerId: type: string format: uuid productId: type: string format: uuid itemId: type: string nullable: true format: uuid resourceId: type: string nullable: true format: uuid lineItemGroupId: type: string nullable: true format: uuid name: type: string scope: type: string enum: - credit_purchase - contract_minimum_amount - plan_minimum_amount - plan_fixed_amount - metric - additional_charge - one_off - tax_gross_up startDate: type: string format: date endDate: type: string format: date totalUsage: type: number nullable: true usageFormat: type: string enum: - unit - currency - null nullable: true subtotalAmount: type: number adjustmentAmount: type: number totalAmount: type: number discountAmount: type: number metadata: anyOf: - type: object properties: type: type: string enum: - metric billingModel: type: string enum: - in_full - proration priceTierDivision: type: string enum: - unique_tier - progressive required: - type - billingModel - priceTierDivision - type: object properties: type: type: string enum: - contract_minimum_amount minimumAmount: type: number minimumAmountApplied: type: number required: - type - minimumAmount - minimumAmountApplied - type: object properties: type: type: string enum: - plan_minimum_amount minimumAmount: type: number minimumAmountApplied: type: number required: - type - minimumAmount - minimumAmountApplied - type: 'null' subLineItems: type: array items: type: object properties: id: type: string format: uuid type: type: string enum: - fixed_price - minimum_amount - price_tier_flat - price_tier_unit - price_tier_package - price_tier_basis_points - proration - unit_price name: type: string description: type: string nullable: true usage: type: number nullable: true amount: type: number metadata: anyOf: - type: object properties: type: type: string enum: - fixed_price fixedPrice: type: number required: - type - fixedPrice - type: object properties: type: type: string enum: - minimum_amount minimumAmount: type: number minimumAmountApplied: type: number required: - type - minimumAmount - minimumAmountApplied - type: object properties: type: type: string enum: - price_tier_flat from: type: number to: type: number nullable: true fixedPrice: type: string required: - type - from - to - fixedPrice - type: object properties: type: type: string enum: - price_tier_unit from: type: number to: type: number nullable: true price: type: string fixedPrice: type: string nullable: true required: - type - from - to - price - fixedPrice - type: object properties: type: type: string enum: - price_tier_package from: type: number to: type: number nullable: true packageSize: type: number price: type: string fixedPrice: type: string nullable: true required: - type - from - to - packageSize - price - fixedPrice - type: object properties: type: type: string enum: - price_tier_basis_points from: type: number to: type: number nullable: true basisPoints: type: number fixedPrice: type: string nullable: true required: - type - from - to - basisPoints - fixedPrice - type: object properties: type: type: string enum: - proration intervalSize: type: number amount: type: string usage: type: number intervalStart: type: string format: date intervalEnd: type: string format: date required: - type - intervalSize - amount - usage - intervalStart - intervalEnd - type: object properties: type: type: string enum: - unit_price price: type: string required: - type - price required: - id - type - name - description - usage - amount - metadata additionalProperties: false adjustments: type: array items: type: object properties: id: type: string format: uuid name: type: string type: type: string enum: - monetary_discount - allocation_offset amount: type: number required: - id - name - type - amount additionalProperties: false required: - id - idempotencyKey - customerId - productId - resourceId - lineItemGroupId - name - scope - startDate - endDate - totalUsage - usageFormat - subtotalAmount - adjustmentAmount - totalAmount - discountAmount - metadata - subLineItems - adjustments additionalProperties: false '400': description: Error object returned to the client. content: application/json: schema: type: object properties: message: type: string description: A human-readable description of the error code: type: string description: A unique identifier for the type of error details: oneOf: - type: object additionalProperties: true - type: array description: >- Additional context about the error, such as invalid fields or constraints. Each endpoint may include specific error details in their documentation causations: type: array description: >- Optional array of error objects following the same structure as the parent error. Only present when there's a meaningful chain of related errors to expose items: type: object properties: message: type: string description: >- A human-readable description of the underlying error cause code: type: string description: A unique identifier for the type of underlying error details: type: object additionalProperties: true description: Additional context about the underlying error required: - message - code additionalProperties: false required: - code - message additionalProperties: false '404': description: Error object returned to the client when a resource is not found. content: application/json: schema: type: object properties: message: type: string description: A human-readable description of the error '409': description: Error object returned to the client. content: application/json: schema: type: object properties: message: type: string description: A human-readable description of the error code: type: string description: A unique identifier for the type of error details: oneOf: - type: object additionalProperties: true - type: array description: >- Additional context about the error, such as invalid fields or constraints. Each endpoint may include specific error details in their documentation causations: type: array description: >- Optional array of error objects following the same structure as the parent error. Only present when there's a meaningful chain of related errors to expose items: type: object properties: message: type: string description: >- A human-readable description of the underlying error cause code: type: string description: A unique identifier for the type of underlying error details: type: object additionalProperties: true description: Additional context about the underlying error required: - message - code additionalProperties: false required: - code - message additionalProperties: false components: securitySchemes: ApiKey: type: apiKey description: API Key Authentication. name: X-API-KEY in: header ````