The preliminary sale agreement: conditions precedent and what to check before you sign

Buying
Écrit par Celia Souralaysak

In Belgium, the preliminary sale agreement (compromis de vente) is not an inconsequential pre-contract. Notaire.be is unequivocal on this: “the preliminary sale agreement is the sale”. Once it has been signed, and barring any condition precedent, neither the buyer nor the seller can withdraw. Anything that has not been checked or provided for at that point will be difficult to put right afterwards, because the notary will draw up the notarial deed (acte authentique) on the basis of this document.

This article reviews the most useful conditions precedent and the checks to carry out before signing a preliminary agreement for a property in the Brussels-Capital Region.

Key point: a preliminary agreement can be drawn up by an estate agent, but notaries recommend at the very least having it checked by a notary before signing. The buyer can choose their own notary at no extra cost, as the fees are shared.

1. Conditions precedent: protecting the buyer without blocking the sale

A condition precedent (condition suspensive) makes the sale dependent on a future, uncertain event. If the event does not occur within the agreed period, the sale is deemed never to have existed. If the event does occur, the sale becomes final.

The mortgage condition

This is the most common clause, and the most important one for a buyer who is borrowing. According to notaries, having a mortgage turned down does not automatically release the buyer: without a properly drafted condition precedent, they could still be bound to buy the property. An effective clause specifies:

  • the amount of the loan applied for;
  • where appropriate, its term and a maximum interest rate;
  • a deadline for obtaining approval (the notaries' brochure gives the example of four weeks);
  • the proof to be provided in the event of refusal (often a letter from the bank) and the number of applications to be made;
  • what happens to the deposit if the condition is not fulfilled.

Too short a deadline exposes the buyer; too long a deadline worries the seller. It is worth talking to your bank before signing so that you can set a realistic deadline.

Other possible conditions

  • Planning condition: for example, that the planning information (renseignements urbanistiques) confirms residential use or the authorised number of dwellings, or reveals no breach.
  • Obtaining planning permission, if the buyer is planning works that require authorisation.
  • Outcome of a survey (soil condition, structure), where doubts remain.
  • Prior sale of another property owned by the buyer, which sellers accept less often.

Each condition must be worded precisely, with a deadline and a clear outcome. Vague wording is a frequent source of disputes.

2. Planning status: checking the legal position

In the Brussels Region, the preliminary agreement must include specific planning information: the property's legal use, permits and certificates issued, known breaches, and whether there is an expropriation plan or heritage protection measure. This information is set out in the planning information issued by the municipality (commune) at the request of the notary or the seller.

This information should be read carefully. A recent example issued by a Brussels municipality in 2026 illustrates its significance well:

  • it describes the legal position (number of dwellings, use, permits issued), which may differ from the actual situation on the ground;
  • it may flag breaches (a conservatory, an altered façade, an unauthorised additional dwelling) that will have to be regularised;
  • it states that it does not regularise any breach unknown to the municipality, and that the absence of a finding does not prove the absence of a breach;
  • it points out that a court may, at a buyer's request, annul their title in the event of a planning breach.

In Brussels, the most sensitive issue often concerns the conversion of a house into several dwellings. You need to check that the number of existing units matches what has been authorised. Notaire.be recommends contacting the municipality's planning department and, if necessary, having the property inspected on site by an architect or surveyor.

3. Certificates and attestations to obtain

  • ⊞ Document | Purpose | Points to watch
  • EPB certificate (certificat PEB) | Energy performance of the home (classes A to G) | Compulsory in Brussels when selling a home; valid for 10 years if the energy characteristics do not change; its details must appear in the listing.
  • Electrical inspection report | Compliance of a dwelling's electrical installation | If the installation is non-compliant, the buyer must notify the inspection body of their identity and the date of the deed, and have a new inspection carried out within 18 months of the deed.
  • Soil certificate (attestation du sol) | Soil condition of the plot (Brussels Environment – Bruxelles Environnement – inventory) | To be provided by the seller before the sale; validity varies according to the plot's category.
  • Planning information | Legal position of the property | Issued by the municipality; to be compared with the actual situation.
  • Post-intervention file (dossier d'intervention ultérieure, DIU) | Information useful for future works | Required for works carried out since 1 May 2001; particularly useful for a renovated property.
  • Co-ownership documents | Financial position and decisions of the co-ownership association | To be received before signing the preliminary agreement (see our dedicated article on co-ownership).

The EPB certificate and renovation prospects

A property's EPB class has a growing impact on its value. Brussels Environment states that the Brussels government has set targets to be met by all homes, with a first milestone in 2033 corresponding to class E or better. According to Test-Achats (January 2026), the corresponding renovation obligations had not yet come into force and their timetable could change. It is wise to find out the status of the legislation at the time of purchase.

The soil certificate

According to Brussels Environment, anyone selling a property in the Brussels Region must provide the buyer with a soil certificate before the sale. Notaire.be adds that, without one, the sale risks being annulled and the seller is liable to penalties. For a plot presumed to be polluted (category 0), a soil survey (reconnaissance de l'état du sol) is in principle required, but the owner of a unit that is not in contact with the ground, such as an upper-floor flat, can apply for an exemption. The certificate is valid for one sale only.

The heating oil tank

If the property has a heating oil tank, ask for the certificate from the latest inspection. In Brussels, Brussels Environment requires buried tanks to be inspected periodically by an expert (every three years for a tank fitted with the required devices). A decommissioned tank must have been emptied, degassed and cleaned, or even filled in. In the event of pollution, a soil survey may be required. These points should be clarified before the preliminary agreement, as they can involve significant costs.

4. The 10% deposit: where and how to pay it

When the preliminary agreement is signed, the buyer usually pays a deposit, often 10% of the price. It is not a legal requirement, but it is customary and serves to secure performance of the sale.

  • It should be paid into the notary's office account, where it remains blocked until the deed is signed. Notaries advise against paying it directly to the seller.
  • The terms “down payment” (acompte) and “security deposit” (garantie) do not have exactly the same legal effect; according to the notaries, a security deposit offers the buyer better protection.
  • If the buyer fails to honour their commitments and the sale is rescinded, the deposit may serve as compensation for the seller.
  • The preliminary agreement must specify what happens to it if a condition precedent is not fulfilled.

5. Other clauses to read carefully

  • Date of the notarial deed: in practice within four months, because registration duties (droits d'enregistrement) must be paid within that period from the preliminary agreement (or from the fulfilment of the condition precedent).
  • Handover of the keys: usually on signing the deed. Notaries advise against early occupation, which, if agreed, must be covered by a written agreement.
  • Condition of the property and latent defects: check the exact scope of the seller's exemption clause.
  • Easements and any tenancy (lease, rental deposit).
  • Co-ownership charges: how calls for funds decided between the preliminary agreement and the deed are apportioned, and what happens to the reserve fund (fonds de réserve).
  • Tax abatement: if you intend to claim the abatement (abattement), its conditions are assessed in particular at the time of the preliminary agreement (for example, not already owning another home outright).

Checklist before signing

  • Agreement in principle or simulation obtained from the bank.
  • Mortgage condition drafted with an amount, a deadline and proof of refusal.
  • Planning information received and understood; authorised number of dwellings checked.
  • EPB certificate, electrical inspection report and soil certificate received.
  • Heating oil tank situation clarified.
  • Co-ownership documents received (for a flat).
  • Deposit to be paid into the notary's account.
  • Preliminary agreement checked by your notary.

This article is for information only and does not constitute personalised legal advice. Every preliminary agreement is different: your notary remains your primary point of contact before you sign anything.

Sources

In conclusion

A well-prepared preliminary agreement protects the buyer as much as the seller. It requires complete documentation and a careful reading of the clauses, ideally with your notary. Living Home Promotion acquires older buildings in Brussels and has them fully renovated by its partner Next Homes before selling the flats. If you are looking for a renovated home in Brussels, discover our property projects.

Celia Souralaysak
Précédent

Verkoopcompromis: de opschortende voorwaarden en de aandachtspunten vóór de ondertekening
Suivant

Compromis de vente : les clauses suspensives et les points à vérifier avant de signer