P85 Query around date leaving the UK and last payday in the UK

Hi HMRC, I am moving abroad, however because I have holidays saved up I will be leaving the UK a week or so before my employment ceases in the UK. As such and due to in being late in the year I have two questions; 1) I will have to do my P85 after I leave the UK due to getting my P45 a few weeks after leaving the UK due to holidays. I wanted to ask if I need to declare my last pay as a one off payment for employment (due to being outside of the UK on payday) or as you already have a record of this from my employer history and it being on my P45 , is there any need for this? 2) Is the P85 legally mandated (I.E do we have to do this) as it is late in the tax year I cannot foresee getting a refund. Thank you in advance! Matt

Hi ,
 

It is in your own interest to notify HMRC of your change of circumstances to endsure that your tax records are as up to date as possible.  This could save you time and inconvenience in the future. Thank you .