Overpayment in terminal pay - can I claim the tax incurred back from HM Forces?

Anyone had any experience of the following and how did they resolve it? I’ve been very significantly overpaid for my terminal reservist mobilisation period (should have been 3 days, ended up getting a full months salary). I’ve told the unit HR office this, and am making arrangements to repay the money.

My concern is tax liability – due to mobilisation, my tax is a bit of a mare at the moment and HMRC have told me to ring them with my P60s at the end of the year to work out how much I owe them or they owe me. I’m expecting a bill of a few hundred quid. However, this payment (one months SO2 salary) is going to significantly increase my tax liability if it shows up on my P60, even though I'll have repaid the money and never actually 'had it'.

Where do I stand on this, regarding repayment and the additional tax. I’m hoping to get it ‘written off’ from my P60, so it doesn’t show up as a calculation. However if it does, and If I pay the money back to the forces, can I claim back the additional tax I’ll have to pay HMRC at the end of the year? This could potentially add a few hundred quid to my bill which I can’t afford.

I’d welcome any guidance as to whether the system can cope with this? Is there a form on JPA for tax rebate? I’m also conscious that possession is 9/10ths of the law, and my view is that I’m not giving them a penny until they confirm I’m not out of pocket. I’ve suggested that if they can’t strike it from the P60, that I hold onto it till I get the tax bill then return it minus the extra amount I had to pay. While I owe them money, its in their interests to sort the problem out, but once they have it back, I cease to be of concern!

Has anyone else had this problem, and if so, how did they fix it?

 

When you are paid the salary, you are debited with the relevant tax amount.

Therefore when you are debited the overpaid salary, you are then credited with the relevant tax amount.

This is of course in an ideal world where everything works as it should !!