These two documents describe the same purchase at two different stages, and confusing them is a common mistake. The compromis (preliminary sale agreement) comes first. It is usually a private agreement between the parties, often prepared with the agency or the notary, and it is fully binding: from the day it is signed, neither side can simply walk away.
The notarial deed comes second, typically within about four months. It is drawn up and signed before a notary, who verifies every legal element, PEB certificate, electrical compliance, soil information, urban-planning status and clear title, and then registers the transfer. Only at the deed does ownership legally pass to the buyer, the balance of the price is paid, and the registration duties and notary costs are settled. Source: Notaire.be.
The point that surprises many buyers: the decisive commitment happens at the compromis, not the deed. People imagine the notary's signature is the moment they could still change their mind, but by then the essential terms have been fixed for months. This is why the conditions written into the compromis, above all a suspensive loan condition, deserve real attention.
The mechanism is the same across Belgium, though the registration duties that the deed triggers vary by region: 3% for an own and sole home in Wallonia since 1 January 2025, against 12.5% for other purchases.
At a glance
| Feature | Compromis (preliminary sale agreement) | Notarial deed (acte) |
|---|---|---|
| Timing | Signed first, at agreement | About 4 months later |
| Signed before | The parties (private) | A notary (official) |
| Legal effect | Binding commitment to sell and buy | Transfers ownership, registered |
| Money | Deposit, often around 10% | Balance of price, duties, notary costs |
| Can you withdraw? | No, both sides are bound | It executes the existing deal |