Late tax return? Here is what to do next
Missed the Self Assessment deadline, or more than one? You are not the first, and it can be put right. The sooner the return goes in, the fewer penalties build up, so we start with the figures and take it from there with you.
ACCA qualified accountants with over 20 years in practice
How the penalties build up
From GOV.UK. Penalties for filing late and for paying late are separate.
| What | Rule or date | Source |
|---|---|---|
| Self Assessment online return | 11:59pm 31/1/2027 (2025/26 return) | GOV.UK (opens in a new tab) |
| Self Assessment late filing | £100; after 3 months £10 a day up to £900; after 6 months 5% or £300 (greater); after 12 months another 5% or £300 (greater) | GOV.UK (opens in a new tab) |
| Self Assessment late payment | 5% of unpaid tax at 30 days, 6 months and 12 months, plus interest | GOV.UK (opens in a new tab) |
| New penalties for all personal returns | From April 2027 the new penalties apply to everyone who submits a personal Self Assessment return | GOV.UK (opens in a new tab) |
What to do now
Get the return in
Daily penalties start 3 months after the deadline, so filing quickly limits them.
Pay what you can
Interest is charged on tax paid late, so paying part of the bill now still helps.
Ask about a payment plan
If you cannot pay in full, you may be able to pay in instalments. HMRC checks the plan is affordable for you.
Appeal if you had a reasonable excuse
Usually within 30 days of the date the penalty was issued.
Reasonable excuses, in plain words
HMRC gives examples of reasonable excuses: a partner or close relative dying shortly before the deadline, an unexpected stay in hospital, or your computer or software failing while you prepared the return.
It also lists things that are not reasonable excuses, including finding the online system too hard to use, not getting a reminder, or a payment failing because there was not enough money. Once the problem is over, the return or payment must be sent as soon as you can.
We help you set out what happened clearly. Whether an appeal succeeds is HMRC's decision, so we never promise an outcome.
If several years are missing
We work through each missing year in turn, starting with the records you have, and tell you where you stand on each before anything is filed. Mistakes found later in a return can be corrected within 12 months of the deadline.
New penalties from April 2027
From April 2027 the penalty points system used for Making Tax Digital applies to everyone who sends a personal Self Assessment return. Getting back on track now means you start the new system with a clean record.
Related help
The tax rules on this page come from GOV.UK and HMRC guidance. Last checked .
Questions about late tax returns
What is the penalty for a late tax return?
£100 at first. After 3 months, £10 a day up to £900. After 6 months, 5% of the tax due or £300, whichever is more, and the same again after 12 months.
Is there a separate penalty for paying late?
Yes. 5% of the tax unpaid at 30 days, 6 months and 12 months, plus interest on the amount owed.
I cannot pay the whole bill. What can I do?
You may be able to set up a payment plan to pay in instalments. HMRC checks it is affordable, and expects savings to be used first.
Can I appeal a penalty?
If you had a reasonable excuse, yes. You usually have 30 days from the date the penalty was issued.
I am owed a CIS refund but my return is late. Is it too late?
Not necessarily. For a sole trader the refund comes through the tax return, so getting the return in is the first step. Overpaid tax can be claimed up to 4 years after the end of the tax year.
Let us help you catch up
No judgement, just a plan. Tell us which years are missing and we will send you a quote, or book a free call to talk it through first.