What the P85 actually does
The P85 does two jobs. It updates HMRC's record so your PAYE position is closed off correctly, and it triggers a recalculation of your tax for the leaving year. PAYE gives you the Personal Allowance in even monthly slices on the assumption you will keep earning until 5 April, so stopping work and leaving part-way through the year normally means you have paid too much; the earlier you leave, the bigger the overpayment tends to be. For an employee of a UK employer going abroad for at least a complete tax year, the P85 has a third job: it is the trigger HMRC uses to issue an NT (No Tax) code so future UK salary can be paid gross where a double tax treaty gives your new country the taxing rights.
P85 or Self Assessment?
GOV.UK is explicit that you do not need to fill in a P85 if you are sending a Self Assessment tax return for the tax year you leave. Landlords, the self-employed, higher earners and anyone else already in Self Assessment report their departure on the SA109 residence pages attached to their return, which is also where split-year treatment is claimed. Our guide to the P85, NT codes and your leaving-year refund walks through every leaving-year form in order.
How the refund reaches you abroad
HMRC pays departure refunds by payable order, and most cheques can only be paid into a UK bank account in your name or a nominee's. HMRC will not pay the fees to convert the money into another currency or send it overseas, so keep a UK account open or line up a UK nominee before you go. Remember the P85 only settles the UK side: your destination country will usually tax you under its own rules once you become resident there, so check the position at both ends of the move.
