# VF-1186

Source: https://xmlvalid.com/rules/VF-1186

> Si EmitidaPorTercerosODestinatario es igual a T el bloque Tercero será de cumplimentación obligatoria.

- Level: error
- Rule sets: VERI*FACTU checks of the AEAT Validaciones 1.2.2 (8 April 2026)
- Context: `/*:RegFactuSistemaFacturacion/*:RegistroFactura/*:RegistroAlta`
- Test: `not($by = 'T') or *:Tercero`

In English: EmitidaPorTerceroODestinatario is T (issued by a third party), so the Tercero block is required.

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