Self-Assessment Deadlines 2025: Don't Miss These Dates

Missing a tax deadline can cost you hundreds in penalties. Here are all the key dates you need to know for the 2024/25 tax year.

Key Deadlines for 2024/25 Tax Year

31 January 2025

• Deadline for online Self Assessment for the 2023/24 tax year
• Payment deadline for any tax owed for 2023/24
• First payment on account for 2024/25 (50% of last year's tax bill)

Late filing penalty: £100 immediately, then more if you're 3+ months late

Late payment penalty: Interest charges start immediately, then 5% penalties at 30 days, 6 months, and 12 months

31 July 2025

• Second payment on account for 2024/25 (the other 50% of estimated tax)

5 October 2025

• Register for Self Assessment if you're newly self-employed

31 October 2025

• Deadline for paper Self Assessment returns (if you still do paper - why?!)

31 January 2026

• Deadline for online Self Assessment for the 2024/25 tax year
• Final payment (balancing payment) for 2024/25
• First payment on account for 2025/26

How to never miss a deadline

1. Set calendar reminders

Put all these dates in your phone calendar with alerts 2 weeks and 1 week before.

2. Use Bosh

We automatically remind you of upcoming deadlines. Plus, since your tax is always up to date, filing takes minutes instead of days.

3. File early

Don't wait until the last minute. File in December or early January and you'll avoid the stress (and the website crashes on 31 Jan).

4. Budget for tax

Put aside 25-30% of your profit for tax. Bosh shows your real-time tax estimate so you always know what you owe.

What if you miss a deadline?

If you miss the 31 January deadline:

• File immediately to minimise penalties
• Pay what you can - penalties are based on unpaid tax
• Consider a Time to Pay arrangement with HMRC if you can't pay in full

Payment on account explained

HMRC assumes you'll earn similar amounts each year. So they ask for 50% of last year's tax bill in January and 50% in July. When you file your return, any difference is settled.

Earned less this year? You can claim to reduce your payments on account - but be sure you're right, or you'll face interest charges.

Stay on top of it

Tax deadlines don't need to be stressful. With Bosh, your tax is always up to date, and we'll remind you when deadlines are approaching. No more last-minute panic.