> For clean Markdown of any page, append .md to the page URL.
> For a complete documentation index, see https://docs.tiankii.com/api-reference/tiankii-api-api-key/payment-requests/invoices/llms.txt.
> For AI client integration (Claude Code, Cursor, etc.), connect to the MCP server at https://docs.tiankii.com/_mcp/server.

# Overview

## Invoices — Base: `/v1/payment-requests/billing-invoices`

An **invoice** is a **bill issued to a customer** (`customerId`): it includes items (`items`), quantity, taxes (`salesTax`), issue and due dates (`invoiceDate` / `dueDate`), PO number and memo. When the customer decides to pay it, it generates a **checkout invoice** (the actual Lightning charge).

It is the `INVOICE` type of the payment request aggregate and is usually extended to a **customer** from the *Customers* folder.

Endpoints:

* **Create** the invoice.
* **Update** the invoice.
* **Send** the invoice by email to one or more recipients.
* **Download** the invoice as a **PDF**.

Everything else (list, pay, activate, complete, delete) uses the common `/payment-requests` routes (*General operations* subfolder).

> ⚠️ **Don't confuse it** with the **Checkout Invoice** folder (`/v1/invoice`): those are the Lightning *charges*, not the issued bill.

Scopes: `Merchant.payment_link.{read,create,update}`.


## API Docs

- Invoices [Create invoice](https://docs.tiankii.com/api-reference/tiankii-api-api-key/payment-requests/invoices/create.md)
- Invoices [Update invoice](https://docs.tiankii.com/api-reference/tiankii-api-api-key/payment-requests/invoices/update.md)
- Invoices [Send invoice by email](https://docs.tiankii.com/api-reference/tiankii-api-api-key/payment-requests/invoices/send.md)
- Invoices [Download invoice PDF](https://docs.tiankii.com/api-reference/tiankii-api-api-key/payment-requests/invoices/download-pdf.md)

## OpenAPI Specification

The raw OpenAPI 3.1 specification for this API is available at:
- [OpenAPI JSON](https://docs.tiankii.com/api-reference/tiankii-api-api-key/payment-requests/invoices/openapi.json)
- [OpenAPI YAML](https://docs.tiankii.com/api-reference/tiankii-api-api-key/payment-requests/invoices/openapi.yaml)