This could be when you had failed to tell us about a change in your income until a few weeks after it had actually gone up.
When we do find out we would need to go back and re calculate your benefit for that period. This would then cause an overpayment.
If you are still getting benefit payments the amount of overpayment outstanding would be recovered from your ongoing benefit. These recoveries would continue until the debt was repaid. If you were no longer receiving payments you would get a bill.
Either way, we would notify you of the amount by letter and would not make recovery for a calendar month. You would also have appeal rights against the decision.