Request ti fill self assesment for the past three tax years

I received three letters requesting to fill the self assesment for the tax for the last three tax years. All letters state: "we looked at your circunstances and you need to complete a self assessmnt tax return" not saying what the circunstances are. Though I register myself for the year 2022/2023 due to High Income Child Benefit as my total income was 53k before taxes for the year, so this explain the request for this year. For the year 2020/2021 income before taxes 17k and for the year 2021/2022 income before taxes 35k. I don't see the reason why i have to fill the self assessment. I work slaried as an employee, no other sources of income. Why i should fill the forms for the 2020/2021 and 2021/2022 Thank You

Hi Mar Lupo
I am sorry you will need to contact HMRC to check why you have be asked to file a Self Assessment for the 2020/21 & 2021/22 tax years Self Assessment: general enquiries.
Thank you.