By the end of December 2015 we will be three-quarters through the current tax year. HMRC used to issue a P161 to those who were approaching 65 to ask them to give details of their income so that they could allocate personal allowances accordingly in the light of their new circumstances. The form is now only issued to those born before 6 April 1938.
What I suggest you do is to call HMRC on the number here either now if you know what your salary to the date you retire will be or as soon as possible after you receive your P45, tell them that have retired and ask them to review your personal tax allowance allocation in light of that fact and that you have taken your state pension. Whether HMRC will be able to allocate your personal allowance in such a way as to ensure that you have paid the correct amount of tax by 5 April 2016 is dependent on the level of your income for the whole year. If they cannot, they may ask you to complete a tax return after the end of the tax year on 5 April 2016.
Alternatively, as HMRC now issue a P800 tax calculation to many taxpayers who are not in self-assessment after the end of a tax year, there may be no need for you to complete a tax return as all your PAYE income will be reported to HMRC by your employer and your pension payers and the Department of Work and Pensions will inform HMRC of your state pension. The P800 shows whether you owe any tax or are due a tax repayment. There is more information on the P800 here.
I hope this helps but let me know if you have any further questions."
Hi again. It's been a few days since I answered your question. Is there anything you need further clarification on?