# FAQ

> Answers to the questions integrators ask first.

Source: /docs/reference/faq

**Is there a sandbox?**

Use a test key (`sk_test_…`). It works against the same API and organization, creates documents flagged `isTest`, and can only submit while the e-invoicing connection is in Test (simulated) mode, where a simulated ASP answers. Test documents are excluded from reports and analytics.

**Do I have to send seller data with every invoice?**

No. Seller name, TRN, address and contact (BT-27 to BT-43) come from the organization profile. If they are incomplete, validation fails with the corresponding business term until the profile is completed in the app.

**Can I supply my own invoice numbers?**

Yes, with `invoiceNumber`. It must be unused. Without it, the next number of the series is allocated atomically. Keep issued tax invoices sequential as required by UAE VAT rules.

**Why did my batch return 400 although some invoices were created?**

Elements are processed independently. The status mirrors the first failure and `extra.results[]` shows every element; those with `success: true` exist. Retry only the failed ones.

**How do I know when the FTA accepted an invoice?**

Subscribe a webhook to `invoice.reported` (and `invoice.rejected`), or poll `GET /invoices/{id}/status` until `invoiceStatus` is `accepted` or `rejected`.

**Can I change an invoice after submission?**

No. Issue a credit note (`381`) or debit note (`383`) with `precedingInvoice: { id }`. Payments, category, cost centre, archive flag and custom fields remain editable through `PATCH /invoices/{id}`.

**Can I get the invoice as a PDF?**

Yes. `GET /invoices/{id}?format=pdf` returns the PDF of any invoice, credit note, debit note or proforma, the same document the app downloads and attaches to emails. `?format=xml` gives the PINT AE XML and `?format=html` a printable version. A 503 is only possible for a received invoice's visualisation when the environment has no HTML-to-PDF service.

**Why is the delivery state 'skipped' when I send an invoice?**

No email provider is configured on that environment. The delivery is logged so the audit trail is complete; configure the provider (Resend) to send for real.

**Which currencies are supported?**

Any ISO 4217 code with `exchangeRate` against AED; `vatAccountingCurrency` covers BT-6. Reporting is in AED.

**How does a CA firm act for its clients?**

Create the key in the firm's organization and send `X-Organization-Id` with the client's organization id on each request. `GET /organizations/managed` lists the ids.

**What is the rate limit?**

600 requests per minute per key; `429` with `Retry-After` beyond that. Batch endpoints count as one request.

**Where is the OpenAPI specification?**

`GET /openapi.json` on the API, and in the API reference tab of this site. `GET /llms.txt` returns a condensed guide for language models.