by mullet on Fri Feb 03, 2012 9:24 am
The refund will probably have been based on you having the personal allowance available for the whole year but having earnings (i.e. having had the personal allowance applied) for only 6 months of the year. So assuming that you get a new job and don't want to underpay tax there is a simple solution, which can be put into place very easily:
1. Don't hand in a P45 to a new employer (you shouldn't have one anyway, as it should have been sent to HMRC in order to create your repayment).
2. When you start a new job, sign the P46 with box C ticked - which will cause you to be taxed at basic rate. Then there should not be an underpayment at the year end (unless you are liable at higher rate). Just explain to the employer that you don't have another job, but you just don't want to be under-taxed. It would then make sense for the new employer to include a simple note to HMRC with the P46, explaining that you had an in-year repayment and that you need to stay on BR (if 20%) or DO (if 40%) until the end of the tax year.
Sample P46 is here. http://www.hmrc.gov.uk/forms/p46.pdf
If you don't get a new job before 5 April, then you have nothing to worry about.