Recoverable tax credit overpayment resulting in underpayment of ESA

Hi,

Client was working (SE) and receiving WTC up until he was diagnosed with cancer. He stopped working and began claiming irESA from November 2017. Client did not end WTC claim as this just completely slipped his mind and therefore his irESA was reflected by the income from WTC.

It has since come to light that the client should not have been receiving WTC. His CTC has been reduced to £3 per week to recover the overpayment by the end of the tax year which is causing hardship to him and his partner

This will mean that client will have been underpaid ESA for the period that he was overpaid TC. I’m wondering whether ESA should be able to pay client the arrears that he is owed for that period? Or whether TC should be considering that the clients ESA award was much less due to the overpayment?

If anyone has any guidance on how to deal with this it would be much appreciated.

Many Thanks

Kate