Social Security Act 1975

11 Where a person has received in respect of any period a payment by way of benefit which disentitles him to a payment which would otherwise be payable to him in respect of that period under a supplementary scheme and he is subsequently found not to have been entitled to the whole or part of the amount of that payment of benefit, any payment under the scheme in respect of that period may, at the discretion of the person by whom the payment falls to be made, be abated by the amount of benefit overpaid or so much thereof as has not been—

(a) repaid or otherwise recovered, or

(b) treated as having been paid on account of any other benefit payable in respect of that period, or on account of an allowance under the Family Allowances Act so payable.