Paying Savings Interest in lump sum NOT through change to tax code

I am employed PAYE and have savings from an inheritance that generated a £600 savings tax bill for the 2022/23 financial year. I paid the tax bill in full when I received the simple assessment in September this year. I intended to do this for two more years (i.e. pay the tax bill when I received it) until my mortgage deal expires, then use the inheritance to pay off my mortgage, leaving me with no further savings tax liability. However, I have now had my tax code changed by HMRC based on the ‘expected’ savings tax bill for next year and as a consequence my pay this month is down £200. I presume this will happen next year too, and the year after, in ever increasing amounts based on the interest rates having gone up since I inherited the money. The savings I have are in fixed term interest accounts and therefore I cannot access the funds. My question is how do I get HMRC to stop taking this savings tax out of my wages, which are completely separate, and instead just pay the tax bill each financial year for the next couple of years? It is utterly contemptible that HMRC take money off you based on what they think you ‘might’ owe them next year.

Hi Jaybird9,
When HMRC receives your savings interest figure we would use this as an estimate going forward.
If your savings interest has changed then you can contact HMRC to amend the estiamte and update your tax code.
Income Tax: general enquiries
Thank you.