Filing tax returns for previous years

I need to file a tax return for the 2020-2021 tax year. How would I do this? Do I have to register for another SA1 form? On a related note, my tax return for this year was submitted using a tax service. Is there a way to confirm that it was received by HMRC?

I tried registering for another SA1 form, but HMRC sent me this: 'Unfortunately we are unable to process your registration form for Self Assessment as our records show that you already have a live Self Assessment record with a Unique Taxpayer Reference (UTR)' I assume it's referring to the 2021-2022 tax year. I had a tax service submit my tax form for that year, so I don't know how to clear that.

Hi kubera,

If you contact our helpline we can can issue a request for the  earlier Self Assessment tax return, and confirm if this years  tax return has been received.

Self Assessment: general enquiries

Thank you. 
 

Hi kubera,

The SA1 form is only needed to register you for self assessment.
Once you have your UTR, you can then file the retruns for the tax years needed.
You do not need to register again for each separate year.

Thank you.