If you start a business this Sept when do you

[trainingdaydenz]

have to do your first Tax self assessment?

You must register within 6 months of starting for self assessment. 1st return would be based on accounts for start to 5/4/25 and due on deadline of 31/1/26.
Accounts can be for full 12 months then just proportioned for the 1st period.

Oh my I think you just made my day.

I've been finding it extremely confusing, so I am going to start off with an accountant.

So just to triple check. My first assessment will be 2026, if I start September 2024?

You would need to submit and pay any tax owed by Jan 2026 but it can take quite a while to sort out so I definitely wouldn't leave it that long!!

You would 'close' your first year on 4/4/25 so theoretically could do the return for that year a couple of weeks after that. I always aim to do my accounts in June

HMRC changed things so all sole traders have to have a year end in line with the tax year, which runs 6th April to 5th April, although you can use 1st April to 31st March.

So if you registered today you'll have a year end of 5th April 2025, and will have from then to 31st January 2026 to submit your tax return. Any payment would also be due on or before 31st January 2026.

Thank you everyone - understood.

I'll definitely get an accountant to ease me in.