The complementaria: appeal Spain’s “second tax bill” after you buy

01A second bill from a different tax office

When you buy a resale home in Spain you self-assess and pay ITP (Impuesto de Transmisiones Patrimoniales) to the regional tax authority (Hacienda autonómica) — not the state agency AEAT. That regional office can, up to four years later, decide the value you declared was too low and issue a liquidación complementaria (locals call it a “paralela”) for the difference, plus interest for late payment, and occasionally a penalty on top.

The key thing owners miss: this assessment is provisional. It is the tax office’s opinion of value, not a court judgment. It can be — and very often is — overturned, because the office must properly justify (motivar) how it reached that value. A desktop valuation that never looked at your specific, perhaps older or defective, property is a classic ground for annulment.

02Why it arrived: the valor de referencia

Since 1 January 2022 (Ley 11/2021), the taxable base for ITP is the Catastro’s valor de referencia whenever that is higher than the price you actually paid. If you declared tax on the purchase price and the reference value was higher, a complementaria for the gap is almost automatic.

The reference value is a presumed value, not an untouchable one. You must pay or declare on it first, but you can then challenge it — by requesting a rectificación de la autoliquidación or by appealing the complementaria — with evidence that the market value is lower: an independent appraisal (tasación), the deed, photos, defects, comparable sales. For older or pre-2022 purchases with no reference value, the office instead runs a comprobación de valores (art. 57 LGT) using expert methods — and those are the most fragile of all.

The Constitutional Court has now settled the general question. In judgment STC 13/2026 of 12 February 2026 (BOE of 19 March 2026) the full court dismissed a challenge to the valor de referencia as the ITP base: the system is constitutional because it taxes average values close to market value and still lets the taxpayer prove a different value. Arguing that the reference value is unconstitutional as such no longer works. What remains is the challenge to your own figure — a rectificación de la autoliquidación or an appeal against the complementaria — where, the court stressed, you may bring any evidence, including an expert appraisal. The tasación pericial contradictoria itself is not available to correct a reference value.

03The three ways to fight it

You have one month from the day after notification. Three routes, and you can combine them:

• Recurso de reposición — an appeal to the very office that issued the bill. Optional, cheap, one month. Often worth it as a first shot when the motivación is weak.
• Reclamación económico-administrativa (TEAR) — a claim before the regional economic-administrative tribunal, one month. You can go straight here (skipping reposición). This is where most badly-justified value checks are annulled.
• Tasación pericial contradictoria (TPC) — you appoint your own expert to counter the administration’s valuation. You pay your expert; a third expert may ask for an advance deposit, and depending on the result you may have to pay that expert too (art. 135.3 LGT). It exists only against a real comprobación de valores — the office checked your declared value with one of the methods of art. 57.1 LGT (an expert report, average market prices, coefficients applied to registry values, insurance or mortgage valuations, the price of other sales of the same property…) and re-assessed the tax on that basis: then requesting it within the month automatically suspends payment of the complementaria, with no guarantee required, and the bill freezes while the values are compared. If your bill simply applies the Catastro’s valor de referencia, the TPC is not available — challenge the reference value itself (rectificación) and use reposición or TEAR.

04Deadlines, payment and suspension

The one-month window is strict. Miss it and the ordinary appeals (reposición, TEAR) close: the bill becomes firme and enforceable — with surcharges if it goes to collection (apremio) — and only the special review routes remain: a request to declare the act null and void (art. 217 LGT), correction of material or arithmetical errors (art. 220) and the extraordinary review of art. 244, each on its own short, closed list of grounds. Do not ignore the letter because it looks intimidating; a complementaria left unanswered is the one that actually costs you.

You do not have to pay to appeal — but appealing does not by itself stop collection. The voluntary payment period of art. 62.2 LGT keeps running while your reposición or TEAR claim is pending; once it ends the debt goes into enforced collection (apremio) with surcharges and interest (art. 161). What stops it is a suspension: automatic if you guarantee the amount (bank aval or deposit — arts. 224.1 and 233.1); without a guarantee only for an arithmetic or factual error or, before the TEAR, where paying would cause harm that is hard to repair (arts. 224.3, 233.4–5); and, where a TPC is possible, automatically without a guarantee by filing the TPC itself (expert fees may still apply) (art. 135.1). Interest keeps accruing in the background, so a fast, well-grounded appeal is cheaper than a slow one — but paying a wrong bill “to be safe” and reclaiming later is the expensive path.

05The classic mistakes (each costs real money)

• Paying it out of fear. The bill is provisional and appealable in one month; most weak value checks are overturned. Paying first, reclaiming later, is slow and often unnecessary.
• Missing the one-month deadline. After it, the ordinary appeals are closed, the assessment becomes firme and heads to enforced collection with surcharges. This is the single most expensive error.
• Not using the TPC when it is available. Against a real value check it is a route that suspends payment without a guarantee while the property is re-valued, but the expert procedure can cost money; other limited no-guarantee suspension grounds also exist; against a valor de referencia bill it does not apply, and people lose the month waiting for it.
• Declaring below the valor de referencia in the first place. If you are still buying, declaring on the reference value (or planning the challenge in advance) avoids the complementaria altogether.
• Assuming the office got the value right. Value checks are routinely annulled for poor motivación — a generic method, no site visit, no account of your property’s real state.