Investment approach
Valuing a flat by transactions: sources, adjustments and price range
Listings show what sellers expect; the registries and the notaries show what sold. How to gather comparables, make adjustments and arrive at a price range rather than a single figure.
Valuing a flat by real transactions means comparing it with similar flats nearby that actually sold, adjusting for the differences and ending with a price range. The sources give different figures: in September 2026 the average asking price in Barcelona on Idealista was 5,462 €/m² (Idealista), while by the registered transactions of the second quarter at the land registrars it was 5,045 €/m² (Colegio de Registradores, ERI). These are different measurements, not an error.
What each price source measures
Each source answers its own question, and mixing them up is dangerous. A listing shows the seller's expectations, the registry shows past transactions, the Catastro (the Cadastre) gives a tax base, and a tasación (a bank valuation) gives the collateral value for the bank.
| Source | What it measures | What it is good for | What it will not show |
|---|---|---|---|
| Portals (Idealista and others) | Asking prices | Understanding sellers' expectations and competition | The price at which deals closed |
| Estadística Registral Inmobiliaria (the registrars' property statistics) | Prices of transactions entered in the registry, averages by city and period | The trend and the order of magnitude of prices | The price of a specific flat: the average mixes different buildings |
| Valor de referencia of the Catastro | A modular value built from notarial transactions with a reducing coefficient | The tax base for ITP (transfer tax) | The market price: by definition it does not exceed the market |
| Tasación | Collateral value under the rules of Orden ECO/805/2003 | The size of the mortgage | What the next buyer is willing to pay |
| Comparable transactions nearby | Prices of closed deals on similar flats | The price of a specific flat after adjustments | Nothing superfluous, but they have to be collected and checked |
The Catastro states outright that the valor de referencia is set every year from the prices of all notarial transactions and does not exceed market value, a reducing coefficient being applied for that purpose (Catastro, frequently asked questions). How it affects tax is covered in the article on the valor de referencia. Why a portal's average price is higher than the transaction price is explained in the piece on the gap between listing and sale.
How to select comparable transactions
A good comparable resembles the flat being valued in the features that move the price most. Selection runs through five filters:
- Place. The same neighbourhood, not the same district: neighbouring blocks in Barcelona differ noticeably.
- Building type. An old building without a lift, a building with a lift after refurbishment and a new build are different markets.
- Floor area and layout. The number of bedrooms matters more than total area.
- Time. The fresher the sale, the better; older ones are adjusted for the movement of the market.
- Condition. Needs renovation, habitable, fully renovated.
There are almost never ideal comparables. Three to five good transactions with adjustments are more reliable than twenty listings without them.
Which adjustments to make and how to record them
An adjustment turns the difference between flats into money, and each one is recorded with its reasoning. The main ones:
- floor and lift;
- condition and the cost of renovation to the required level;
- orientation, light, view;
- terrace and balcony;
- parking and trastero (storage room), if included in the price;
- fees to the comunidad (owners' association) and approved but unpaid derramas (special assessments).
Worked example, not a forecast. An 80 m² flat on the third floor with a lift is being valued, needing a cosmetic refresh. Three nearby transactions are found.
| Comparable | Sale price | How it differs | Adjustment | Price after adjustment |
|---|---|---|---|---|
| A, 80 m², 4th floor, renovated | 480,000 € | The renovation is already done | minus 40,000 € | 440,000 € |
| B, 85 m², 3rd floor, needs renovation | 430,000 € | 5 m² larger | minus 25,000 € | 405,000 € |
| C, 78 m², 3rd floor, 10 m² terrace | 470,000 € | A terrace | minus 30,000 € | 440,000 € |
The range after adjustments is 405,000–440,000 €. If the flat is listed at 495,000 €, the gap to the top of the range is 55,000 €, and that is a subject for conversation with the seller, not a reason to agree. The adjustments in the example are conventional: their size depends on the neighbourhood and the specific building.
What the flat's own history adds
The history of the listing completes the comparison. How long the flat has been on the market, whether the price has been cut and how many times, whether it was withdrawn earlier, why it is being sold. A flat that has not sold for months at the current price is itself a sign that the price is above the market. The signs of overpricing are collected in the article on how to tell a flat is overpriced.
What the result of a valuation should look like
The result of an honest valuation is three figures, not one: a reasoned range, an opening offer and a ceiling above which the buyer does not go. The housing market is not a stock exchange, and a flat has no exact price until it is bought.
If the purchase is for renovation and later sale, a calculation of the maximum entry price from the future sale price is added to the range; see the piece on the entry price.
When valuing by transactions does not work
The method weakens where there are few transactions or the properties are too different. A villa in Pedralbes, a penthouse with a large terrace, the only house of its kind on the street: there may be no comparables, and then it is more honest to widen the range and say openly that the accuracy is low.
It also does not work as a substitute for a tasación for the bank: the bank will accept only the report of an approved appraiser. DNPI Capital values a specific flat by transactions with adjustments as part of its property value analysis.
Questions and answers
How can I find the real market value of a flat in Spain?
Compare it with similar flats nearby that actually sold, with adjustments for floor, condition, light, terrace and the building's costs. The registrars' statistics and the valor de referencia give the background, but not the price of a specific flat.
Can a flat be valued from portal prices?
Only very roughly. Portals show asking prices, and overpriced flats stay on them longest, so comparing with listings usually inflates the valuation.
Is the valor de referencia equal to the market price?
No. As the Catastro explains, it is set from the prices of notarial transactions with a reducing coefficient and does not exceed market value. It is a tax base, not a valuation of the market.
How many comparables are needed to value a flat?
Usually three to five well-chosen transactions in the same neighbourhood are enough. The quality of the comparables and the reasoning behind the adjustments matter more than their number.
How does a market valuation differ from a tasación?
A tasación is made for the bank by a company approved by the Banco de España, under prudence rules. A market valuation by transactions is for negotiating the price, and one does not replace the other.
