5Numbers
National register number
Need to put a Belgian national register number in a form and want to be sure it was copied right? Loket checks the format and the check digits, and nothing else.
Eleven digits, with or without dots and a dash.
Personal data: Loket checks it in your browser only. Nothing is kept or sent; leave the page and it's gone.
The counter is open. Type or paste something in the field.
How it works
The number reads YY.MM.DD-SSS.CC: the date of birth, a serial number and two check digits. Those are 97 minus the remainder of the first nine digits divided by 97; for people born from 2000 on, with a 2 put in front of those nine digits.
A BIS number, for people not in the national register, has the same layout with 20 or 40 added to the month. Loket recognises both.
A valid number doesn't mean it exists or whose it is. Loket keeps nothing, sends nothing and never puts the number in the page address.
Sources
Rules as they stand in Loket on 3 October 2026.
Loket is an independent tool by nealvdv, not a government service. A check here is a calculation, not an official confirmation.