Missed the Self Assessment Deadline? Here’s What You Can Do Now

19 May

The 31 January deadline for filing your Self Assessment tax return has passed — but it’s not too late to get back on track.

Every year, thousands of self-employed people, landlords, and small business owners miss the deadline for filing their tax return or making their payment to HMRC. Whether you forgot, felt overwhelmed, or just didn’t have everything ready — don’t panic. But do act quickly.

Here’s everything you need to know about what happens if you’re late, how to fix it, and how to avoid things getting worse.

What Happens If You Miss the 31 January Deadline?

Missing the tax return deadline can lead to automatic fines — even if you don’t owe any tax.

Here’s a breakdown of the HMRC penalties:

1 day late: £100 fixed penalty
3 months late: £10 per day, up to £900
6 months late: Extra £300 or 5% of tax due (whichever is greater)
12 months late: Additional £300 or 5% of tax due — potentially more if HMRC believes you’re deliberately withholding

Important: These penalties stack, and you may also be charged interest on late payments. So the sooner you file, the better, even if you’re missing some documents.

What If You Can’t Pay the Tax You Owe?

Even if you file your return, you might not be able to pay everything you owe right away. That’s okay — but you need to communicate with HMRC.

Your options:

Make a partial payment now
Anything you pay reduces your interest charges and shows you’re trying to meet your obligations.
Set up a Time to Pay plan
HMRC allows you to set up a payment plan for debts under £30,000. You can usually do this online through your Government Gateway account if your return is filed and you’re within 60 days of the deadline.
Speak to an advisor
If your situation is more complex — for example, if you’ve missed multiple deadlines — it’s worth getting help to speak to HMRC on your behalf.

What About Payments on Account?

If your tax bill for the year is more than £1,000 and less than 80% of your tax was already collected at source (like PAYE), you’ll usually have to make ‘payments on account’.

These are advance payments towards your next year’s tax bill, due in two instalments:

31 January (same as your main tax bill)
31 July

If you’ve missed the January deadline, it’s likely your July 31 payment on account is still due, unless you’ve applied to reduce it. Don’t ignore it — missing this payment can also result in interest and penalties.

What to Do Next

Here’s how to get back on track:

File your tax return as soon as possible
Even if it’s late, getting your return in now can stop more penalties from building up. Don’t wait for the “perfect” paperwork, submit what you can, and amend later if needed.
Pay what you can
You’ll be charged interest daily until your bill is paid. A part-payment is better than nothing.
Set up a payment plan if needed
Use HMRC’s online service or speak to an advisor if you’re unsure.
Get help if you’re struggling
You don’t have to face this alone. We’ve helped lots of small business owners file overdue returns, deal with HMRC, and get back in control.

You're Not Alone — And It's Not Too Late

Missing the deadline doesn’t make you a bad business owner — it makes you human. What matters now is taking action.

At RGR Payroll & Accounting Services, we help people just like you catch up on tax returns, organise their finances, and move forward with confidence. Whether you’re behind for the first time or this is a recurring problem, we’re here to help without judgment.

Need help filing a late return or dealing with HMRC?
Let’s talk, we’ll make it as stress-free as possible.

Want to stay ahead next year?
Sign up for our monthly newsletter and get access to our free Monthly Bookkeeping Guide — a simple way to stay on top of your finances all year long.

Lucy Taylor