I've just done mine today. Absolutely loathe it.
My finances are deliberately simple. The online ID palaver , registration, log in, and pages and pages of multi choice questions, are torture based on Chinese whispers.
It's like those spy dramas where the dastardly suspect is interrogated for hours with the same questions over and over until he trips himself up . I confessed to being in UK do not farm, no secret lodgers in the attic, I got rich from a cold weather payment. HMRC tortured me until I folded and agreed to give them everything they wanted When they made me go to the bank to get the money my bank texted a dire warning the demand was probably criminal, "Tell nobody nuthink!"
Too late. If you don't tell, HMRC unleash the dogs of hell, online assistants who aren't even human.