If you challenge the Catastro reference value and get it annulled, the tax office can then open a valuation check on your home, but not in just any way: it will have to appraise the property individually and, as a general rule, send an expert to inspect it inside and out. Spain's Supreme Court made this clear in a ruling of 16 July 2026, which rejected valuing a house on the basis of cadastral data, aerial photos and a picture of the façade taken from Google Maps.
It affects anyone who buys a resale home, inherits or receives a gift of property in Spain, including on the Costa del Sol: since 2022 the reference value has been the minimum tax base, and challenging it has a downside that is rarely mentioned.
What is the reference value and why does it set what you pay?
It is a value that Spain's Directorate General for the Cadastre calculates every year for each property, based on the sales signed before a notary in its area. To keep it below market value, a reduction factor of 0.9 is applied, in other words a 10% discount. It should not be confused with the cadastral value used for the annual IBI property tax, which is usually much lower.
Since 1 January 2022, the reference value has been the minimum base for three taxes: transfer tax (ITP) when you buy a resale home, stamp duty (AJD) on the deed for a new-build purchase, and inheritance and gift tax. If the price you pay is higher, you are taxed on the price; if the reference value is higher, you are taxed on that.
Take an example in Andalusia, where the standard ITP rate is 7% (the regional government has announced it will cut it to 6.75% in 2027): if you buy a home in need of renovation for €300,000 and its reference value is €340,000, you will pay €23,800 in tax instead of €21,000, which is €2,800 more.
The upside of paying tax on the reference value is legal certainty: if you declare that value or a higher one, the law prevents the tax office from opening a valuation check to claim more. That peace of mind is partly lost when you challenge it.
How do you challenge the reference value?
It cannot be appealed on its own before the Catastro. You first have to pay the tax and then ask for your self-assessment to be corrected, or appeal the assessment if it is the tax office that issues one. In Andalusia the decision lies with the Andalusian Tax Agency, but it must first obtain a mandatory, binding report from the Directorate General for the Cadastre that confirms or corrects the value in light of your evidence.
The most common grounds are errors in the floor area, use or age recorded in the Catastro, or a state of repair worse than the calculation assumes, such as a house that needs a full renovation. What usually tips the balance is evidence: an appraisal or an expert report with photos of the interior.
What happens if you win? The three possible outcomes
| Outcome of the challenge | What you pay | Can the tax office check the value afterwards? |
|---|---|---|
| You do not challenge it, or you lose | Tax on the reference value or the price, whichever is higher | No: the law rules it out |
| The Catastro lowers the value | Tax on the corrected value or the price, with a refund of any overpayment | In principle no: the tax base is still tied to the reference value |
| The reference value is declared non-existent | Tax on the highest of the declared value, the price and the market value | Yes: it can open a valuation check |
The third scenario is the tricky one. The Catastro may conclude that a home has no reference value when it falls outside its methodology: for example, a property under construction with no finishes or utilities, or one that bears little resemblance to the type of home used to calculate values in its area. For price-capped social housing or homes bought at auction, the criteria are not consistent.
Without a reference value, the tax base becomes the value you declared in the deed, unless the price or the market value is higher, and the tax office regains the power to check it. In other words, winning the challenge can open a second front.
Can the tax office value your home using Google Maps?
No. In ruling 923/2026 of 16 July (appeal 6851/2024), the Supreme Court overturned the tax assessment that the regional government of Extremadura had issued to the buyer of a home with a parking space in Badajoz. The 2018 purchase had been recorded in the deed at €120,000, and the authorities raised the value to over €201,000, 67.6% more.
The authorities valued the property without setting foot in it: their expert relied on cadastral data, aerial orthophotos and an image of the façade from Google Maps, and justified skipping the visit with reasoning almost identical to that used in another case. The buyer's reports, by contrast, showed a run-down interior in need of a full renovation.
The court set out the following criteria, which apply to any valuation check based on an expert report:
- The general rule is a personal visit by the expert to the property, outside and inside.
- It can only be skipped exceptionally, with a justification based on specific data about that property explaining why it is not needed.
- Cadastral data are designed for mass valuations, not for appraising a specific home.
- A photo of the façade says nothing about the condition inside, the quality of the finishes or the need for renovation.
- The fact that the taxpayer can request a contradictory expert appraisal does not lower the standard required of the authorities.
The case predates 2022, but its doctrine applies in full when the reference value disappears: the tax office will have to start almost from scratch and justify the new figure with an individual valuation, especially if it tries to arrive at an amount similar to the one that was annulled.
When is it worth reviewing the reference value on the Costa del Sol?
With prices rising, the reference value of a home in good condition usually ends up below the agreed price, because it is calculated from past sales and with that 10% discount. In that case you are taxed on the price and the reference value does not affect you. As a guide, these are the asking prices in some municipalities according to our October 2026 market report:
| Municipality | Median asking price (€/m²) | Lower quartile (€/m²) |
|---|---|---|
| Marbella | 6,096 | 4,549 |
| Fuengirola | 5,417 | 4,144 |
| Malaga | 4,955 | 3,693 |
| Estepona | 4,750 | 3,757 |
| Mijas | 4,367 | 3,364 |
| Costa del Sol total | 4,738 | 3,523 |
These are asking prices, which are higher than final sale prices, so they are not a like-for-like comparison. But if the reference value per square metre of a home in need of renovation comes close to these medians, or even exceeds them, that is a sign to review it before you pay the tax.
These are the cases where the problem comes up most often:
- Homes in need of renovation, because the Catastro calculation cannot see the condition of the interior.
- Purchases below market value, such as an urgent sale or a sale between relatives.
- Inheritances and gifts, where there is no price and the reference value is almost always the tax base.
- Unusual properties, or those with incorrect Catastro data on floor area, use or age.
What should you do if the tax office opens a valuation check?
- Ask for the full file and the expert's report.
- Check whether there was a visit: the date, photos of the interior and a description of the actual condition.
- See whether the valuation is individual or relies only on cadastral data, coefficients or generic comparables.
- Gather your own evidence: photos, renovation quotes or a report from an appraiser or an architect.
- Consider requesting a contradictory expert appraisal, which pits the tax office's valuation against that of your own expert and suspends collection of the assessment.
- Meet the deadlines: you have one month from notification to file an appeal for reconsideration or an economic-administrative claim.
Conclusion: challenge it, but with a strategy
Challenging an excessive reference value is still a good idea when you have evidence, but do it knowing that, if it is annulled altogether, the tax office may come back for more. The Supreme Court ruling sets a high bar: without an individual appraisal and, barring a justified exception, without a visit, a new valuation is likely to fall apart.
At EVS PROPERTY GROUP we go through the reference value and the taxes on each purchase with you before signing, so you know how much you will pay and whether there is room to negotiate. If you are considering buying on the Costa del Sol, get in touch and we will look at your numbers.
This article is for general information only and is not a substitute for a tax adviser’s advice on your specific case.
Frequently asked questions
Can the tax office check the value if I pay ITP on the reference value?
No. If you declare the reference value or a higher figure, the law prevents the tax office from opening a valuation check on the property. That protection disappears if the reference value is annulled and the tax base becomes the value you declared.
What happens if the reference value is higher than the purchase price?
You pay ITP on the reference value. If you believe it exceeds the home's real value, you can ask for your self-assessment to be corrected and provide evidence, such as an appraisal, and the Catastro will issue a binding report confirming or correcting it.
How long do I have to challenge the reference value?
You can ask for your self-assessment to be corrected as long as the right has not become time-barred: generally four years from the end of the filing period. If the tax office issues an assessment, you have one month from notification to appeal it.
Where can you look up a home's reference value?
On the Catastro's online portal, using the cadastral reference and the date of the transaction. You need an electronic ID to download the certificate; if you do not have one, your notary, lawyer or tax adviser can obtain it.
What next? The most useful thing after reading is to look at the real market: browse properties by city or tell us on WhatsApp what you are looking for — area, budget, timing — and we will prepare a tailored selection, with no obligation.
You may also find useful: sell your property invest on the Costa del Sol free valuation monthly price report
