Hi jswme,
We are aware that not all customers are able to provide the necessary ID confirmation to enable them to open a personal tax account.
The procedure to set one up is here:
Personal tax account: sign in or set up
If you are unable to set one up, then you will need to call us and we can give you details of which years you may be able to pay on a voluntary basis.
However, HMRC are unable to confirm if paying any deficient years will improve your pension entitlement.
I suggest you call the DWP first, their number is 0800 731 0175 and they are open 8.00am to 6.00pm Monday to Friday.
They will tell you your current pension position and which (if any years) can be paid to improve it.
They should then be able to transfer you to HMRC and we will give you payment instructions.
With regard to your letter, as I am not aware of the full contents, I can only speculate on which are will be dealing with it.
The area I suspect has your letter is currently working on letters received on 7 December 2022.
Thank you.