A friend lives and works (and is paid) abroad. He has rental income from a flat in the UK (around £5,000) and a small amount of interest on UK accounts. For the first time, HMRC required completion of a SA form for 2018-19, which he did when back in UK during last summer.
HMRC accepted that foreign pay is irrelevant, and no tax is owed on UK interest, but have asked for 20% tax on rental income (so £1,000 - half by 31 January and half later), as no personal allowance was used. He is a UK citizen, so qualifies for personal allowance without any further requirements. Although this fact was included on the SA forms, it seems from what I've read since that personal allowance has to be explicitly claimed each year!
So, whilst in UK again for Christmas, he completed the form to claim personal allowance and sent this back to HMRC (with a note referencing their calculation). Nothing has come back so far, so the question is, should the first payment be made this week, knowing it will have to be refunded later, or can he wait for their response? We are both new to SA, so have no experience of what happens, and want to avoid late payment penalties (which we think are quite high?). Any suggestions, please?