Hello, I did some short-term work September and October 2020. (collectively I was paid £3100 for this). I didn't realise that this wouldn't be paid via PAYE at the time. I'm a bit overwhelmed by the information and have never filled out a self-assessment form before. Do I just have to fill out the SA1 form and send online? My Income (less my allowances) for April 2020 - April 2021 was £28379.36. Many thanks in advance.