You can’t stop your Child Benefit if you’re using it to pay back an overpayment (or to pay back certain other benefits from another country).
Responsibilities after your Child Benefit stops
You must pay any tax charge owed for each tax year up to the date your Child Benefit stops.
Use the Child Benefit tax calculator to work out what you owe each tax year and when it’s due.
Even after your payments stop, you must report any changes in your family life that affect your entitlement to Child Benefit.