Overpayment of IS- ‘offsetting’ against potential WTC/CTC award

Think I may have posted something similar before but it’s Friday and I’m not at my best.

Situation is as follows; Client has been told they have been overpaid IS as in 2009 they allegedly failed to disclose they were cohabiting with a person who was working. This is under dispute under the normal criteria in R(SB)17/81.

It is fairly clear that if they were in fact a couple they would be entitled to a large payment of WTC and CTC. Even if the client was prepared to admit that they were a couple from 2009 the CTC and WTC can’t be backdated to then.

I know that the amount recoverable cannot be offset by the potential CTC/WTC award as they are different benefits and different agencies paying them but could it be submitted that only the loss to the public purse as a whole (not to any particular agency) is the only amount recoverable.

I have a recollection of a Judge quashing an overpayment on similar grounds but I did not see any reference to any specific law or case law that would give authority to the proposition.

Any thoughts or references gratefully recived