PAYE tax payer suddenly asked to submit tax returns for 2020 to 2023 - how do I do this?

I am a PAYE tax payer suddenly asked by HRMC to submit tax returns for 2020/21, 2021/22 and 2022/23 - how do I do this? I have been through my HRMC account - all my P60s are in my account for these years. I have not changed employer during this period or done any other work. No help from HRMC chatbot or phone system which keeps kicking me out. Unclear guidance from HRMC on what to do. Do I now have to do self assessment for these 3 years? How can I do this retrospectively? The info would be as per my P60s. Any advice?

Hi ShonaghY,
You can file the tax returns back to 2020/21 online. You would need to set up a online account and enrol to file the tax return online:
File your Self Assessment tax return online.
To check why the notice to file the Self Assessment tax return was issued you will need to contact: HMRC Self Assessment: general enquiries.
Thank you.