Overpayment of holiday pay - How to recover on payroll

We have to recover overtaken holiday from a leaver who left last month. P45 has been issued..when we are entering this onto the payroll system as a negative holiday amount, the net to recover is the same as gross due to tax code 0T. How do we get around this. We are unable to open month 8 and amend as this is what some links suggest, as payroll is closed. Thanks,

Hi You would just work out the net overpayment not the gross and amend the tax month that this was overpaid. The ability to amend previous FPS should be a facility available in your software so we would advise you speak to your software provider. Thank you