The ordinary way to secure a claim is to ask a judge for permission to seize. Belgian law knows an exception for attachment in the hands of a third party — typically the debtor's bank: on the strength of an unpaid invoice alone, a bailiff can freeze what that third party owes your debtor, before any judgment exists. The money does not come to you yet; it stops moving. In a file where you fear the account will be empty next month, that is the difference between recovering and filing a claim in an insolvency.
Four conditions, all of them required
1. The debt is certain, established and due. An invoice with a due date that has passed and an amount that is not in doubt. Estimates, provisional amounts and claims for damages do not qualify.
2. There is urgency. You must have a genuine reason to fear that your debtor will not be able to pay later: no reaction to formal notices, annual accounts not filed, other attachments already levied, staff leaving, the company address abandoned.
3. Formal notice was given. A written demand, ideally by registered mail, should as a rule come first. It is also what makes point 2 demonstrable.
4. The invoice was never validly disputed. A debtor who protested the invoice properly and in time takes this route off the table — which is exactly why the timing and the wording of a dispute matter so much (see our article on this topic).
What happens after the freeze
Four things, in our experience, in roughly this order of frequency. The debtor pays, because a frozen account is an operational emergency and cheaper to solve than to fight. Or you proceed to a judgment and convert the protective attachment into an executory one, and the money is paid out. Or the debtor challenges the attachment before the attachment judge, and you defend it. Or the debtor goes bankrupt — in which case the attachment is unwound, but at least you learned the truth early instead of after another six months of promises.
What it costs
The bailiff's fees are advanced by you and can be recovered from the debtor. Reckon on roughly €500 to €1,000, depending among other things on the size of the claim. That advance is the real decision point: this is a powerful step against a company that has money and will not pay, and a waste against one that has nothing left. It is precisely the question a solvency screening answers before you spend anything.
Not sure which of the two you are dealing with? A SolvaClear screening tells you what the debtor owns, what other creditors already seized, and whether this step is worth taking — for €80.