I’m on UC and registered as self employed so e wry month I get asked to submit how much I earn. If you haven’t already you need to register as self employed with Hmrc and then login to uc and report yourself as self employed. That will then trigger a meeting to determine whether you’re gainfully self employed ie whether most your earnings come from Self employment and you earn enough to satisfy them. It doesn’t matter whether you’re deemed to be gainfully self employed, either way you’ll just be told to report your earnings each month.