Missed the Self Assessment deadline?

What happens when you miss 31 January

The deadline for filing your Self Assessment return online is 31 January, and any tax you owe for the year is due on the same day. If your return is not filed by then, HMRC charges late filing penalties automatically. They grow the longer the return stays unfiled:

• Straight away: a £100 penalty, even if no tax is due
• After 3 months: £10 a day for up to 90 days, up to a maximum of £900
• After 6 months: a further 5% of the tax due or £300, whichever is greater
• After 12 months: another 5% of the tax due or £300, whichever is greater

The £100 penalty catches people out because it applies even when there is nothing to pay. If you needed to send a return, a business loss or only a small amount of self-employed or rental income does not stop the penalty.

File as soon as you can

Once the £100 has been charged, it is tempting to think the damage is done. It is not. The next penalties start at 3 months, then 6 months, then 12 months, so every week you wait brings the next stage closer. Filing the return stops the late filing penalties from growing any further.

Do not wait until you have the money to pay before you file. Filing late and paying late are treated separately, so getting the return in limits one problem even if you cannot fix the other yet. Filing online is the quickest way to get it in.

If you do not have every figure, do not let that stop you starting. A missing bank statement or a few lost receipts can usually be worked around, and the sooner someone looks at what you have, the sooner the return can go in.

Pay what you can

Interest is charged on tax paid late, so paying part of the bill now reduces what builds up while you sort out the rest. Even a partial payment helps.

If you cannot pay the full amount, contact HMRC rather than ignoring it. HMRC may agree a payment plan if you cannot pay in full, but it expects you to get in touch, and it helps if your return has been filed so the bill is known.

If you had a reasonable excuse

You may be able to appeal a late filing penalty if you had a reasonable excuse for missing the deadline, for example a serious illness or a bereavement close to the deadline. HMRC decides each case on its facts, so there is no guarantee an appeal will succeed.

Even with a reasonable excuse, you are expected to file as soon as the problem has passed. Being busy, or not having the money to pay, is unlikely to count. If you think you have grounds, file first and appeal alongside it. HMRC's penalties page explains how to appeal.

How we can help

We prepare and file late Self Assessment returns. Whether it is one return a few weeks late or more than one tax return still outstanding, the process is the same: find out what is missing, gather the records and get the return in.

1. 1

   Free call

   Tell us which tax returns are outstanding and what records you have.

2. 2

   Gather records

   We send a clear list of what we need, such as bank statements, invoices, receipts and details of any other income.

3. 3

   Prepare and check

   We prepare the return and go through the figures with you before anything is filed.

4. 4

   File and plan payment

   We file the return and tell you what to pay and when.

If more than one return is outstanding, we work through them one at a time, starting with the oldest. Once you are up to date, we can keep you there, with your next Self Assessment tax return prepared well before it is due.

Who it's forThis is for sole traders, freelancers, landlords and company directors who have missed the deadline, or know they are about to.

Making sure it does not happen again

Most late returns come down to the same thing: the records are not ready, so the return keeps getting pushed back. A few habits change that:

• Keep your books through the year. If your income and spending are recorded monthly, the return becomes a check rather than a scramble. Our bookkeeping services are built for exactly that.
• Know the dates. The tax year runs from 6 April to 5 April. If you are newly self-employed, register by 5 October after the end of the tax year. Returns and payment are due by 31 January, and payments on account are due on 31 January and 31 July.
• Do not leave it until January. You can file as soon as the tax year ends. Getting it done early means you know what you owe in good time.

Making Tax Digital for Income Tax also changes the routine for some people. From 6 April 2026, sole traders and landlords with qualifying income over £50,000 must send quarterly updates through compatible software, followed by a final declaration. The threshold falls to £30,000 from April 2027 and £20,000 from April 2028. There is more on what that means on our pages for landlords and freelancers.

If you run a limited company, your company has its own deadlines too. Our page on year-end accounts and Corporation Tax explains them.