> For the complete documentation index, see [llms.txt](https://chekin.gitbook.io/chekin-public-api/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://chekin.gitbook.io/chekin-public-api/api-reference/einvoicing.md).

# eInvoicing

This API is designed for creating and managing invoices in the Chekin system.

### Provider Reference

The system supports multiple invoicing providers for different countries. Each provider has an internal code used in the API and a common name used in the documentation.

| Internal Code | Common Name | Country       | Tax Authority         |
| ------------- | ----------- | ------------- | --------------------- |
| `MY_DATA`     | MyData      | Greece (GR)   | MyData                |
| `AT`          | AT          | Portugal (PT) | Autoridade Tributária |
| `AADE`        | AADE        | Greece (GR)   | AADE                  |
| `ADE`         | AdE         | Italy (IT)    | Agenzia delle Entrate |

{% hint style="warning" %}
`AADE` is used **exclusively** for Short-Term Stay Declarations (not for traditional invoices). `MY_DATA`, `AT` and `ADE` are used for standard invoice issuance.
{% endhint %}

### Process Overview

#### For invoice providers (MyData / AT / AdE)

1. [Creating a supplier](/chekin-public-api/api-reference/einvoicing/suppliers.md) (invoice issuer)
2. [Creating invoice items](/chekin-public-api/api-reference/einvoicing/invoicing-items.md)
3. [Obtaining sub-totals](/chekin-public-api/api-reference/einvoicing/invoices/retrieve-sub-totals.md)
4. [Issuing the invoice](/chekin-public-api/api-reference/einvoicing/invoices/issue-an-invoice.md)
5. [Issuing a credit note](/chekin-public-api/api-reference/einvoicing/invoices/issue-a-credit-note.md), if necessary

#### For AADE (short-term declarations only)

1. [Creating a supplier](/chekin-public-api/api-reference/einvoicing/suppliers.md) (with AADE credentials)
2. [Creating a short-term declaration](/chekin-public-api/api-reference/einvoicing/short-term-declarations/create-declaration.md) per booking

{% hint style="info" %}
Invoice issuance is **asynchronous**. An invoice is created with status `NEW`/`PENDING` and then processed in the background. Track the result by polling [List Invoices](/chekin-public-api/api-reference/einvoicing/invoices/list-invoices.md) or by configuring [webhook notifications](/chekin-public-api/api-reference/einvoicing/webhooks/invoice-webhooks.md) on the supplier.
{% endhint %}

### High-Level Provider Comparison

| Feature                          | MyData (`MY_DATA`)                     | AT (`AT`)         | AADE (`AADE`)         | AdE (`ADE`)       |
| -------------------------------- | -------------------------------------- | ----------------- | --------------------- | ----------------- |
| Country                          | GR                                     | PT                | GR                    | IT                |
| Traditional invoices             | ✅                                      | ✅                 | ❌                     | ✅                 |
| Short-term declarations          | ❌                                      | ❌                 | ✅                     | ❌                 |
| Standard invoice                 | ✅                                      | ✅                 | ❌                     | ✅                 |
| Receipt                          | ✅                                      | ✅                 | ❌                     | ✅ (optional)      |
| Credit note                      | ✅                                      | ✅                 | ❌                     | ✅                 |
| Retail sales credit note         | ✅                                      | ❌                 | ❌                     | ✅ (optional)      |
| Item categories                  | `standard`, `fee`, `accommodation_tax` | `standard`, `fee` | `standard`            | `standard`, `fee` |
| Workspace required               | ✅                                      | ✅                 | ❌                     | ❌                 |
| External credentials in supplier | ❌                                      | ❌                 | ✅ (username/password) | ❌                 |

See [Provider differences](/chekin-public-api/api-reference/einvoicing/provider-differences.md) for a field-by-field summary, and [Definitions & FAQ](/chekin-public-api/api-reference/einvoicing/definitions-and-faq.md) for an explanation of the objects involved.