How to Challenge a Tax Value Assessment on Your Spanish Property (Comprobación de Valores)

Complete guide to challenging tax value assessments (comprobación de valores) on Spanish property purchases. Learn about appeals, expert counter-valuations and deadlines to avoid paying more ITP or inheritance tax than you should.

You bought a property on the Costa Blanca for €200,000, paid 10% Transfer Tax (ITP) — €20,000 — and thought the deal was done. Then a letter arrives from the regional tax authority: they say your property is actually worth €250,000, and you owe an additional €5,000 plus interest. Welcome to the comprobación de valores — and, more importantly, your right to fight back.

This guide explains exactly what a tax value assessment is, how the Spanish authorities calculate it, and what legal remedies you have if you disagree.

What Is a Comprobación de Valores?

A *comprobación de valores* is a formal procedure through which the Spanish tax administration — typically the regional (*autonómica*) tax authority — checks whether the value you declared when paying a tax (most commonly ITP on a property purchase or Inheritance & Gift Tax / ISD) matches the legally established parameters.

Since the Ley 11/2021 (anti-fraud law) came into force, the key parameter is the Cadastral Reference Value (*valor de referencia del Catastro*), which now serves as the minimum taxable base for ITP, ISD and Wealth Tax. If you declared a value below the reference value, the tax authority can — and routinely does — issue a supplementary assessment demanding the difference.

A Practical Example

You purchase a flat in Torrevieja for €200,000 and self-assess ITP at 10% = €20,000. However, the Cadastral Reference Value for that property is €250,000. The Valencian tax authority (*Conselleria d'Hisenda*) sends you a *liquidación complementaria* for:

  • Additional taxable base: €50,000
  • Additional ITP at 10%: €5,000
  • Plus late-payment interest from the date of purchase

If you do nothing, you pay. But you have three distinct legal avenues to challenge this.

The Legal Framework

The procedure is governed primarily by:

  • Article 134 of the General Tax Act (*Ley 58/2003, LGT*): establishes the formal requirements — the administration must issue a formal opening, grant a hearing and deliver a reasoned decision
  • Article 57 LGT: lists the permitted methods of valuation (expert reports, market data, cadastral coefficients, reference values)
  • Ley 11/2021: introduced the Cadastral Reference Value as the minimum base for ITP, ISD and Wealth Tax
  • Real Decreto 1065/2007: development regulations for the LGT