Just to say, I have just come off a call with HMRC. The adviser told me my Self Assessment status was 'dormant', that I would have to re-register to file an SA Tax return this year, and that I had missed the 5th October deadline. She was actually quite insistent and almost aggressive. Turns out her 'advice' was also wrong. To quote HMRC online pages: "You must register for Self Assessment before using this service if you’re filing for the first time or you’ve sent a tax return in the past but did not send one last tax year". I had filed SA returns last tax year and the year before. My SA account is not dormant, I have no need to re-register and was able to start my SA immediately. The adviser could do with some additional basic training in HMRC rules.