A Under Portuguese law, an urban property must correspond to the architectural project approved by the City Council and the elements in the Habitation Licence (Licença de Utilização) – the approved plans form part of the administrative procedure that authorised the construction. Where the physical building diverges from those plans, the issue does not automatically invalidate a sale, but it does introduce legal, administrative and transactional considerations that should be addressed carefully.

The first and most important distinction is between minor, non-structural alterations and material modifications. Internal changes that do not affect structural elements, or alter the external appearance of the property, or increase the gross construction area, are generally viewed as lower risk.

By contrast, works that increase the total construction area, alter façades, enclose terraces, convert garages into habitable accommodation or add annexes may constitute unauthorised construction if no amendment to the original licence was obtained. In legal terms, these works may fall outside the scope of the approved project.

The consequences depend on a combination of factors, including the date of the works, the planning regime in force at the time, and whether the alterations would comply with current municipal planning instruments, such as the Plano Diretor Municipal (PDM).

Portuguese planning law provides for limitation periods in respect of administrative enforcement. In many cases involving properties constructed more than 30 years ago, the municipality’s power to impose fines or order demolition will have lapsed, but the expiry of enforcement powers does not amount to formal regularisation. This means that the property may still be technically non-compliant from a documentary standpoint, which can be relevant in the context of a sale.

From a conveyancing perspective, discrepancies are usually identified during the buyer’s legal due diligence. The purchaser’s lawyer will typically request certified copies of the approved plans, the building licence and the Habitation Licence, and will compare these with the current configuration of the property.

Where mortgage financing is involved, a bank-appointed surveyor may flag inconsistencies; even where the risk of enforcement is negligible, documentary misalignment can delay completion or affect negotiations.

Before placing the property on the market, it is prudent to carry out a preliminary assessment. An architect or civil engineer can prepare an updated ‘as built’ survey and provide a technical opinion on whether the differences are material. If the alterations meet with current planning rules, a retrospective regularisation procedure may be available; this involves submitting updated drawings, technical responsibility declarations and other documentation required, together with payment of the applicable administrative fees. The Câmara will then assess whether the works can be formally legalised – successful regularisation significantly strengthens the property’s market position.

Early legal advice is equally important. A lawyer can evaluate potential exposure and advise on disclosure obligations. Under Portuguese civil law, a seller must not conceal known irregularities that could affect the value or intended use of the property. Where discrepancies exist, they should be disclosed transparently and addressed in the Promissory Contract (Contrato-Promessa de Compra e Venda). In high-demand areas in the Algarve, buyers may accept minor irregularities, especially in cash transactions, but reliance on market tolerance should not replace legal assessment.

In conclusion, discrepancies between approved plans and the existing structure are not uncommon in older Algarve properties and do not automatically prevent a sale. Nevertheless, they should be treated as a legal matter requiring careful evaluation.

A combination of technical review, analysis of planning compliance and tailored legal advice will enable you to determine how best to structure the transaction. By addressing the issue before marketing the property, you minimise uncertainty, protect yourself from future liability and facilitate a smoother and more secure sale process.