HMRC Payments on Account

Afternoon All,

I have a client who has made two payments on account, this has resulted in an over payment this year and he is due a rebate, however he also has to make a payment on account for next year.

Does anyone know what the revenue will do?? i.e will they pay him the over payment and he still makes the payment on account in Jan or will they off set one against the other??

Thanks for your help
Have a great Christmas!
Julie