Self Assessment deadline checklist: what to do before 31 January 2026

If self assessment is on your to do list, the online deadline is 31 January 2026 (for the 2024/25 tax year).

Here’s a practical checklist to help you get it done without a last minute scramble.

1. Check you are filing the right year

For the tax year 6 April 2024 to 5 April 2025, the online filing deadline is 31 January 2026. If you’re unsure whether you need to file at all, it’s worth checking your HMRC account (or ask your accountant/bookkeeper).

2.  Gather your paperwork

Start with one folder (digital is fine) and collect:

·        Your income records (invoices, sales reports, bank statements)

·        Business expenses (receipts/invoices, mileage log if you claim mileage)

·        Bank and card statements (business and relevant personal if mixed)

·        Interest statements (savings accounts)

·        P60/P45 if you were employed at any point

·        Dividend vouchers (if you run a Ltd company)

·        Pension contributions and Gift Aid (if applicable)

If you’re missing bits, don’t panic make a quick list and request what you need now.

3.  Do a sanity check on your numbers

Before you submit, do these quick checks:

·        Does your income match what arrived in the bank?

·        Are there any obvious missing months or big gaps?

·        Are any personal expenses sitting in business costs?

4.   Watch out for payments on account

If your tax bill is above a certain level, HMRC may ask for payments on account, basically paying some of next year’s tax in advance. That can make the January amount feel bigger than expected. 

5.   If you can’t pay in full, don’t ignore it

You still need to file on time. Then, if payment is the issue, get in contact with HMRC for advice.