The Self Assessment deadline for the 2024-2025 tax year is fast approaching, and every year HMRC issues millions of penalties simply because people miss it or assume they don’t need to file.
Here’s the thing.
If HMRC expects a return from you and you don’t submit it on time, penalties apply automatically even if you don’t owe any tax.
This guide is a straightforward reminder of who must file a tax return for 2024-25, what information you need, and what happens if you miss the deadline.
Key deadline for 2024-2025
- 31 January 2026
- Deadline to:
- Submit your online Self Assessment tax return
- Pay any tax owed for the 2024–2025 tax year
- Make your first payment on account (if applicable)
Miss this date and penalties start immediately.
Who needs to file a tax return for 2024-2025?
You must submit a Self Assessment tax return if any of the following apply during the 6 April 2024 to 5 April 2025 tax year:
Self-Employed and Contractors
- You were self-employed or a sole trader
- You earned over £1,000 in self-employment income
- You worked under CIS (Construction Industry Scheme) and had tax deducted
Company Directors
- You were a director of a limited company (unless it was unpaid and very limited)
High Earners
- Your total income was over £100,000
- You received Child Benefit and you or your partner earned over £50,000 (High Income Child Benefit Charge)
Rental and Investment Income
- You earned income from property or renting
- You received dividends, savings interest or investment income not fully taxed at source
Other Common Reasons
- You had foreign income
- You made capital gains (sold shares, crypto, or property)
- HMRC sent you a notice to file (this alone means you must submit)
If you’re unsure, assume you do need to file until confirmed otherwise.
What you need to file for 2024-2025
Here’s what most people need to prepare before submitting:
Income Details
- Self-employment income and expenses
- CIS statements (monthly deduction statements)
- Employment income (P60, P45)
- Rental income
- Dividend and savings income
- Foreign income (if applicable)
Allowable Expenses and Reliefs
- Business expenses
- Mileage and vehicle costs
- Home office use
- Pension contributions
- Gift Aid donations
- Professional fees
Other Information
- Student loan details
- Child Benefit received
- Capital gains calculations
- National Insurance contributions
Getting this right matters. Errors can lead to underpaid tax, HMRC enquiries, or penalties later.
What happens if you don’t file on time?
This is where people get caught out.
Automatic Penalties
- £100 penalty the day after the deadline, even if no tax is owed
- After 3 months: daily penalties up to £900
- After 6 months: extra penalty of 5% of the tax due (or £300)
- After 12 months: another 5% or £300 added
Interest on Unpaid Tax
- Interest is charged daily until paid in full
HMRC Enforcement
- Tax estimates raised by HMRC (often higher than reality)
- Collection action or debt recovery
- Impact on mortgage or loan applications
Once penalties start, they stack quickly.
If you can’t pay by 31 January 2026
You should still file your return on time.
HMRC is far more flexible about payment plans than late filing.
Options may include:
- Time to Pay arrangements
- Spreading payments monthly
- Reducing penalties by acting early
Filing late removes most of these options.
Already filed before? Still check this year
Even if you’ve filed before, things change:
- Income increases
- New side work
- CIS deductions
- Rental or investment income
- Child Benefit rules
Assuming “nothing changed” is one of the most common mistakes.
How Tax2u can help
At Tax2u, we help people file correctly and on time every year by:
- Confirming whether you need to file
- Checking all allowable expenses and reliefs
- Submitting your 2024–2025 return accurately
- Reducing tax where possible
- Avoiding penalties before they start
👉 If you haven’t filed yet, now is the time to act.
Final reminder
- Tax year: 6 April 2024 – 5 April 2025
- Deadline: 31 January 2026
- Miss it: penalties apply automatically
- Unsure: get advice before the deadline