Does the rate of recovery of an overpayment depend on the total annual TC award or the award during the prevailing relevant period?

My client was overpaid in 03-04. At the beginning of the current year she was entitled to more than the family element of CTC by virtue of child care costs. A deduction of 25% was levied on the award to recover the overpayment.

Her child care ceased in July leading to a new relevant period in which she will be entitled to the family entitlement of CTC only.

I suspect the 100% recovery rate will now be levied even though across the full year she will have been entitled to more than £545.