People often confuse an official, certified valuation (tasación) with an automated AI valuation. They aren't the same thing, they aren't used for the same purpose and they don't have the same legal standing. Understanding when you need each one saves you from costly mistakes.
The official valuation: when it's compulsory
The official valuation, carried out by a Sociedad de Tasación (a valuation company) approved by the Bank of Spain, is a legal requirement in two main situations:
- To apply for a mortgage: The bank needs an official valuation to set the reference value on which it grants the loan (generally 80% of the lower of the purchase price and the valuation).
- For certain legal proceedings: Disputed inheritances, divorces with a division of assets, and some mortgage foreclosure situations.
In these cases there's no alternative: you need the official valuation, which costs between €250 and €500 and takes 3-10 days.
The AI valuation: what it's ideal for
An AI valuation (AVM) has no legal standing for bank transactions, but it's very useful for:
- Deciding whether an asset is priced at market value before making an offer
- Comparing multiple assets in different areas with the same metric
- Checking prices at no extra cost (most tools are free or low-cost)
- Analysing portfolios of many assets, where an individual valuation for each property would not be financially viable
- A first filter before paying for an official valuation
The best strategy: use them in sequence
The most efficient process for a buyer or investor: first, check the price with an AI valuation to decide whether it's worth going any further. If the AI valuation confirms that the price is reasonable or below market value, then you pay for the official valuation for the mortgage. That way you avoid paying for valuations of properties that you later discover are overpriced.
The margin of error of each one
Official valuations have a margin of error of 5-10% in normal markets (valuers are conservative by nature and because regulation requires them to be). Well-calibrated AI valuations in data-rich markets have an average error of 3-7%. In low-liquidity markets (rural areas, highly unusual properties), the AI's margin of error can be larger.
Check the value before you buy: Go to RadarPro to get AI valuations of assets all over Spain, or read how AI property valuation works.
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