Tax returns quick question please please!

[DrowningInSellotape]

I am dyslexic and typing very slowly in order to get numbers right. Can someone pls clarify for me.
If you did a tax return for 2019-2020, is it correct that it would relate to all income for 2018-2019, or for 2019-2020? I'm assuming April-April for tax return and for income.
I need to check over bank statements and I think tax always relates back to the previous year so I need to make sure I'm looking at correct year on statements.
I know this is a stupid question. But please can someone clarify. On Google etc it just confuses me more. Thank you!

Your 19/20 Tax Return relates to income between 6th April 19 and 5th April 20.

A 2019/20 tax return is for everything between 6th April 2019 and 5th April 2020, and would have been due to be submitted by 31st January 2021 (although this was extended to end of Feb 21 due to covid).

The 19-20 tax return would have been due by 31 Jan 2021 so yes working up to a year behind is possible.

Ah ok I need to check when the return was actually submitted, it seems that might be where I'm getting the year in arrears thing from?

Yes I think that's where you are getting confused with the previous year thing, HMRC obviously don't expect you to submit your tax return the day after the tax year ends give you until the following January 31st. So,

19-20 due 31st Jan 21
20-21 due 31st Jan 22
21-22 due 31st Jan 23

and so on

As I said in my first post though the deadline has been extended the last couple of years due to covid.

Thank you SO much 😊