With an existing property, most of what you are buying can be seen, measured and surveyed. With an off-plan property, what you are buying is described rather than shown: a plan, a schedule of areas, a specification of finishes and a delivery promise. The documents replace the viewing.

The timeline is also different. Payment is normally staged across the construction period rather than concentrated at the deed, which means money is committed before delivery. That changes what matters in the contract: security for sums paid, evidence of progress, and clear consequences if the project is delayed or not completed as described.

Finally, the counterparty is different. You are usually contracting with a developer or a project company rather than a private seller, so understanding who that entity is — and what it owns and controls — is part of the diligence rather than a formality.

An off-plan purchase follows a longer arc than an ordinary purchase, because the period between commitment and delivery can span months or years. The stages below describe the shape most projects follow. The actual sequence, deadlines and documents depend on the development and the contract.

A reservation is often presented as a small, low-commitment step. In practice it usually sets a deadline for signing the CPCV, fixes the price and the unit, and involves a payment whose refundability depends entirely on the wording of the document.

Before reserving, the useful questions are simple: is the unit clearly identified, is the price complete, how long does the reservation last, what has to happen before the CPCV, and in what circumstances is the reservation amount returned, retained or credited against the price.

Off-plan diligence is documentary. It looks at four connected layers: who the developer is, what the development is and how far it has been approved, what your specific unit is, and what the contract actually commits the developer to deliver.

Renders, brochures and show units communicate an intention. The contract and its annexes communicate an obligation. The gap between the two is the single most common source of disappointment in off-plan purchases, and it is almost always avoidable by reading the annexes as carefully as the brochure.

The practical test is whether every feature you are relying on appears somewhere in the contractual documents, with enough precision to be enforceable: the plan, the schedule of areas, the specification of materials and equipment, and any list of what is included or excluded.

Off-plan purchases are normally paid in stages linked to the reservation, the contract and progress on site, with a balance at completion. The structure differs from project to project, and the contract is what controls it.

The CPCV (Contrato de Promessa de Compra e Venda) is the binding promissory contract. In an ordinary purchase it mainly fixes price, deposit and completion date. In an off-plan purchase it does considerably more: it defines the property that does not yet exist, the standard to which it will be built, when payments fall due, when it must be delivered and what happens if it is not.

Because so much depends on it, the CPCV in an off-plan purchase is normally reviewed alongside the project documentation rather than in isolation — the contract's promises only mean something if the licensing, the plans and the specification support them.

During construction the buyer's role is mostly to monitor: confirming that milestones certified for payment correspond to real progress, keeping records of every payment, and staying aware of licensing steps that the project still has to complete.

Changes during construction are not unusual. Materials become unavailable, technical constraints appear, and buyers themselves often request variations. What matters is whether the contract allows change unilaterally, whether an equivalent standard must be maintained, whether you must be notified, and whether a material change gives you any right to object or withdraw.

Buyer-requested variations deserve the same discipline as the original specification: agreed in writing, priced, and reflected in the contractual documents rather than in an email exchange with the sales team.

Delay is the most common friction point in off-plan purchases. Construction programmes, licensing steps and utility connections all sit outside the buyer's control, and the completion date in the contract is often expressed with permitted extensions.

Rather than assuming a delay will or will not happen, the practical approach is to understand in advance how the contract treats it: what the target date really is, what extensions are allowed and for what reasons, at what point delay becomes a breach, and what remedies exist if it does.

Before completion there is normally an opportunity to inspect the finished unit against the contract: the plan, the areas, the specification and any agreed variations. This is the moment when the documentary promises are compared with the physical result, and it is far easier to resolve issues before the balance is paid than afterwards.

Handover also has an administrative side. Licensing, the technical file, utility connections, meter readings, condominium constitution and keys all need to line up, and the property's registration and tax records should reflect the completed building.

Financing an off-plan property is not identical to financing an existing one. Lenders assess a property that is not yet complete, valuations may be carried out at different stages, and funds are usually released at or near completion rather than in step with the developer's milestones. That can create a gap between when the developer wants payment and when a lender is willing to pay.

Offer validity is the second issue. Mortgage offers have expiry dates, and an off-plan completion can move. Non-resident buyers should also account for currency movements across a long payment schedule, since instalments are paid over time rather than at a single moment.

Off-plan purchases attract the same categories of purchase cost as other Portuguese purchases: transfer tax (IMT), stamp duty (Imposto do Selo), notary and registration costs, and professional fees. Purchase taxes are normally settled around the deed rather than at the reservation or CPCV stage, so the cash requirement is not evenly spread.

The classification of the property matters for how those taxes are calculated, and classification is not something a brochure can settle. Where a development is licensed for tourism, the assumption that residential treatment applies may not hold.

None of the following are exotic. They are the ordinary ways an off-plan purchase becomes harder than it needed to be.