# Issue Vietnamese e-invoices (hóa đơn điện tử) through an API

Ha Tang issues e-invoices under your tax code through your own account at your e-invoice provider (see the full guide for the supported providers). Connect the account once in **Payments settings → Invoice providers**, then either add an `invoice` block to a payment, so the invoice is issued once the order is paid, or create one on its own.

**With the payment** (issued when it is paid)

```ts
import { Hatang } from "@hatang/sdk";

const hatang = new Hatang(); // HATANG_API_KEY with payments:write

const { data: payment, error } = await hatang.payments.createOrder({
  order_id: "SO-1002",
  amount: 275_000,
  ipn_url: "https://shop.example.com/api/hatang/ipn",
  invoice: {
    mode: "publish",
    buyer: { name: "Nguyen Van Khach", tax_code: "0109876543", email: "accounting@example.com" },
    items: [{ name: "September service plan", quantity: 1, unit_price: 250_000, vat_rate: 10 }],
  },
});
```

The IPN and `payments.get` carry the invoice's status and number (`payment.invoice`).

**On its own**, for example for a bank transfer received without an order

```ts
const { data: invoice, error } = await hatang.einvoices.create({
  mode: "publish",
  transaction_id: "txn_123",
  buyer: { name: "Nguyen Van Khach" },
  items: [{ name: "Coffee beans 1 kg", quantity: 1, unit_price: 91_667, vat_rate: 8 }],
});
```

In `development`, connect the provider's demo account: the invoices are real sandbox invoices but never reach the tax office.

## Go further

- Connecting the provider, the lifecycle, drafts, failures and replacements: [E-invoices](https://hatang.dev/docs/guides/payments/einvoices.md)
- Payments the invoice can follow: [Accept VietQR bank transfers](https://hatang.dev/docs/guides/recipes/vietqr-payments.md)

Source: https://hatang.dev/docs/guides/recipes/einvoice-api