Suppose client, when single, had been overpaid TC. S/he then makes a joint claim with a new partner. HMRC seek recovery. Can they reduce the couple claim to recover that overpayment, eventhough the new partner has no liability for the client's own (single claim) overpayment?

Many thanks

Had a client in this position and TCO said they had no power to recover from couple claim under these circumstances. In the end, recovery was waived on hardship grounds, so I never did get to the bottom of whether they were correct or not.

No, they cannot reduce one claim to recover an overpayment from a previously terminated claim. In this case it appears to make sense, but you'll have fun when you come across the same members of a couple who seperated for a week or two, notify TCO, then get back together again and again notify TCO. They'll have the original claim terminated and have to complete a fresh claim form, then their new claim will not be linked in any way to their old claim so if there's an overpayment TCO will be paying them with one hand and taking direct recovery of the overpayment with the other (with an awful lot of messy admin in between).