Tax on reduced income following retirement

I am currently working full time and am an additional, 45%, tax payer (self-assessment). I am also receiving a workplace pension which, because it is in addition to my salary, is all taxed at 45%. I retire in May 2025 when my only income will be my pension. This is considerably lower than my current income. How do I ensure that from May my pension is not all taxed at 45%? Thank you.

Hi,
When you retire, contact us by webchat or phone via Income Tax: general enquiries- we can project your income for the rest of the tax year, and amend your tax
codes to ensure you pay the right amount of tax.
Thank you.