3rd October 2025Getting Ahead: Key 2025 Self-Assessment Dates

With the self-assessment deadline now on the horizon, there’s no time like the present to ensure your return reaches HMRC on time. We outline who needs to file tax returns and shares tips to avoid common pitfalls as the tax deadline draws near.

What You Need to Know

The deadline for HMRC to receive your paper tax return is 11:59 pm on 31 October 2025. If you’re posting your return, don’t use that date as just a ‘send-by’ date, make sure it arrives on time, or you will risk a penalty.

The safer, and more convenient option for most, is to file online. This way your deadline extends to 11:59 pm on 31 January 2026.

Know whether you need to file, stay organised with your paperwork, and give yourself a buffer for postage or unexpected last-minute snags.

Who Needs to File?

You will need to complete a Self-Assessment tax return if you:

• Are self-employed or received untaxed income over £1,000
• Have income from renting property (e.g. Airbnb), savings, investments, or dividends
• Received foreign income or have other non-PAYE sources
• Made a capital gain (in certain circumstances)
• Were a partner in a partnership
• HMRC has issued you a notice to file

That list is not exhaustive, when in doubt, check HMRC or consult a tax advisor.

What’s New for 2025?

This year, HMRC has rolled out improved digital tools to make managing tax easier.

Taxpayers can now set up flexible weekly or monthly Budget Payment Plans through their app, helping to spread the cost of their bill ahead of January. The app also allows you to file your return, check your account, and track payments, all designed to reduce the stress of last-minute filing and give you greater control.

Common Pitfalls to Avoid

1. Don’t wait until the last minute. Gathering documents (like your P60, P45, or expense records) can take longer than expected.
2. Claim the tax reliefs you’re entitled to. Record pension contributions and Gift Aid donations to reduce your tax bill.
3. Keep a copy of your return and the records used. For employed filers or pensioners, retain records for at least 22 months; self-employed individuals and landlords should hold onto documentation for 5 years and 10 months.

Why File Early?

Filing your return sooner rather than later brings peace of mind and a host of benefits:

• Learn what you owe sooner and plan payments or set up a payment plan if needed.
• If you’re owed a refund, you may get it faster.
• Have proof of income on hand for things like mortgages or loans.
• Avoid late-filing penalties and interest charges.

2025 Self-Assessment Timeline at a Glance

• 5 October 2025: Register for Self-Assessment if you’re filing for the first time, you’ll receive a UTR number.
• 31 October 2025: HMRC must receive your paper tax return by this date to avoid penalties
• 31 January 2026: File your return online (and pay any tax due)
• 6 April 2026: If you’re a sole trader or landlord with income over £50,000 you’ll need to use Making Tax Digital (MTD) for Income Tax