Pension/ Tax releif above £50,270

I have decided to invest what ever I earn over the threshold of £50,270 into my pension. I understand that I will receive 20% releif at source and that I will need to claim for the other 20% via self assesment for the amount over the threshold. I have read online that after the first year of doing this for example tax year 24-25 i can claim back the other 20% back in April 2025 and will receive a lump sum for the amount owed for yearv24-25. I also read that future years my tax code would change as HMRC will assume that i will be paying the same amount in every year. As i will be earning different amounts every year based on future guaranteed pay rises and overtime, the change in tax codes could become very confusing from year to year and I wouldnt really know where I stand and also not sure what would happen if I had to stop the extra contributions for some reason in the future?. My question is instead of my tax code changing every year am I able to fill out a self assesment form and receive a lump sum every year so that my tax code stays the same 1257L? If not could you tell me how this would work if say in 24-25 if I earned £60,270 and invested £10,000 into my pension above the threshold amount and how it would affect my tax code the following years? Thank you

Hi If you don't know the answer to my post could you let me know who to contact please. Thanks John

Hi

Personal pension relief payments are declared in box 1 of page TR4 of the tax return (SA100).  Have a look at Tax on your private pension contributions.  
The amount claimed in your tax return is automatically transferred to your tax code for the following tax year.  
If you discover that this figure will be wrong, you will need to contact our self assesment helpline on 0300 200 3310 or contact our webchat facility at Contact HMRC, to amend/remove the personal pension figure.
In the current tax year, you can claim tax relief up to the lower of a maximum of £60000 our your annual earnings paid into pension schemes.  
Any payment that exceed your threshold, becomes a 'pensions savings tax charge' and the excess should be declare on SA101 (additional information) box 10 on page Ai4 or in the online equivalent box
"Amount saved towards your pension, in the period covered by this tax return, in excess of the Annual Allowance". 
Have a look at Tax on your private pension contributions.

Thank you