# LINE_MAIN_TAX_REQUIRED

Each line must specify its main tax (main_tax). No default tax is applied.

<Callout type="info">
**Category:** [Invoices](/errors/category/invoicing)
</Callout>

## Rules that cite this code

- [SIM-004 · A simplified invoice still carries its minimum contents](/rules/simplified#sim-004)

## Example response

When this error occurs, the API returns a JSON response with the following shape:

```json
{
  "type": "https://docs.beel.es/errors/LINE_MAIN_TAX_REQUIRED",
  "title": "LINE_MAIN_TAX_REQUIRED",
  "detail": "Each line must specify its main tax (main_tax). No default tax is applied.",
  "instance": "/v1/<resource>",
  "errors": [],
  "success": false,
  "error": {
    "code": "LINE_MAIN_TAX_REQUIRED",
    "message": "Each line must specify its main tax (main_tax). No default tax is applied.",
    "details": {}
  },
  "meta": {
    "timestamp": "2026-05-21T10:00:00Z",
    "request_id": "4bf92f3577b34da6a3ce929d0e0e4736"
  }
}
```

The `type` URI is stable and always resolves to this page.

## Message

<Tabs items={["English", "Spanish", "Catalan"]}>
  <Tab value="English">{"Each line must specify its main tax (main_tax). No default tax is applied."}</Tab>
  <Tab value="Spanish">{"Cada línea debe indicar su impuesto principal (main_tax). No se aplica ningún impuesto por defecto."}</Tab>
  <Tab value="Catalan">{"Cada línia ha d'indicar el seu impost principal (main_tax). No s'aplica cap impost per defecte."}</Tab>
</Tabs>

Send the request with `Accept-Language: <es|en|ca>` to receive the message in your preferred language.

## Other errors in this category

<div className="grid grid-cols-2 gap-3 not-prose">
  <Card title="ATTACH_SOURCE_INVOICE_UNAVAILABLE" description="A source invoice is not available (it does not exist or you no longer have access); uncheck the source invoices attachment to send without the folder" href="/errors/ATTACH_SOURCE_INVOICE_UNAVAILABLE" />
  <Card title="ATTACH_SOURCE_INVOICES_NO_SOURCES" description="The invoice has no consolidation disbursements: there are no source invoices to attach" href="/errors/ATTACH_SOURCE_INVOICES_NO_SOURCES" />
  <Card title="ATTACH_SOURCE_INVOICES_REQUIRES_PDF" description="Attaching the source invoices also requires attaching the invoice PDF" href="/errors/ATTACH_SOURCE_INVOICES_REQUIRES_PDF" />
  <Card title="ATTACH_SOURCE_PDF_MISSING" description="These source invoices have no generated PDF: ‹value›" href="/errors/ATTACH_SOURCE_PDF_MISSING" />
  <Card title="ATTACH_SOURCE_ZIP_TOO_LARGE" description="The source invoices ZIP (‹value› MB) exceeds the maximum sendable size (‹value› MB)" href="/errors/ATTACH_SOURCE_ZIP_TOO_LARGE" />
</div>

## Keep exploring

<div className="grid grid-cols-2 gap-3 not-prose">
  <Card title="All Invoices errors" description="Every code in this category in one table." href="/errors/category/invoicing" />
  <Card title="Error reference home" description="Browse every category or jump to the handling guide." href="/errors" />
</div>

---

Full OpenAPI spec: https://docs.beel.es/api/openapi