Real estate due diligence in Spain: what to verify before buying

Real estate due diligence is the verification process that must be carried out on a property before committing to purchase it. It is not an optional formality or a precaution for extreme cases: it is the step that allows the buyer to know with certainty what they are buying and whether there are problems that affect the price, the viability of the transaction or the buyer's peace of mind once they are the owner. This guide covers the four areas that must always be verified.

The Land Registry: the first search

The Land Registry (Registro de la Propiedad) is the first database to consult in any property transaction in Spain. It contains the official description of the property, the identity of the registered owner and all charges, encumbrances or limitations that affect the property.

The nota simple (a basic registry extract) is the standard document: it records the current owner, a description of the property — floor area, boundaries, registry reference — and existing charges. It can be obtained electronically at low cost. However, for a thorough due diligence it is worth going beyond the nota simple and requesting a copy of the full registry history, which shows prior transfers and the origin of any active charges.

The most common charges that can appear are mortgages not cancelled at the registry — even if the debt has been paid, if the cancellation was not registered it will still appear — easements of passage, liens or preventive annotations from ongoing legal proceedings. Each has different implications: some can be resolved before closing, others can be sufficient reason to reconsider the transaction.

Community debts and IBI

An aspect that does not appear in the Land Registry but can generate significant costs is the property's situation with respect to the owners' community and the local property tax (IBI — Impuesto de Bienes Inmuebles).

The seller is obliged to present at the time of the notarial deed a certificate from the building's administrator confirming the flat is up to date with community payments. However, that certificate only reflects the situation at the date of issue. For a more complete check, it is worth asking the community or the administrator directly whether there are approved deramas (special community levies) pending execution — building works that will be charged in the coming months — as these do not always appear in the standard certificate.

IBI is the local authority property tax. Unpaid IBI creates a debt with the local council that follows the property, not the owner: if you buy a property with outstanding IBI, you inherit that debt. Requesting from the seller the last four paid IBI receipts — the standard prescription period — is a basic verification that should not be skipped.

Planning status and licences

The planning status of the property is an area that surprises buyers coming from countries where this check is not standard. In Spain, particularly in older properties, there are cases of floor area built without a licence, works carried out without notifying the local authority, or uses not permitted under planning regulations.

The tool for checking is the municipal planning report, which can be requested from the local authority. It verifies that the property has the correct classification, that there are no open penalty proceedings and that the registered floor area matches the cadastral reality.

For new-build properties, planning due diligence focuses on the first-occupation licence — which certifies that the building has passed local authority inspections and is authorised for habitation — and the completion certificate issued by the supervising architect. Without these documents, no contract should be signed. The guide on buying new-build property in Madrid covers in more detail the specifics of due diligence for this type of transaction.

Due diligence for non-resident buyers

Non-resident buyers have some additional considerations in the due diligence process that are worth anticipating.

The first is the fiscal verification of the transaction: in a sale where the seller is non-resident in Spain, the buyer is legally obliged to withhold 3% of the declared purchase price and pay it to the Tax Agency (AEAT) as a retention of non-resident income tax (IRNR). If the seller is resident, this retention does not apply. Verifying the seller's fiscal residence before completion avoids surprises at the notary.

The second is coordination with the bank if the transaction requires mortgage financing. Spanish banks conduct their own valuation of the property and may refuse to finance if there are uncancelled charges or planning irregularities. Having completed due diligence before submitting the mortgage application prevents the process from stalling at an advanced stage.

For a complete overview of the entire purchase process as a non-resident — from the NIE to the notarial deed — the guide on how to buy a flat in Madrid as a non-resident is the most useful starting point.

At Aedara we coordinate due diligence as part of the purchase process, with lawyers specialising in property law. If you are at the stage of analysing a property in Madrid, tell us where the transaction stands.

References

Colegio de Notarios de España. (2026). Notarial fees and procedures.

Dirección General de Catastro. (2026). Cadastral values.

Banco de España. (2026). Mortgage regulation.