How much is the penalty for filing a Self Assessment tax return late?

The initial penalty is £100, charged automatically after the 31 January deadline. After 3 months, HMRC adds £10 per day (up to £900). At 6 months and 12 months, a further £300 or 5% of the tax due (whichever is higher) is charged.

What is the current HMRC late payment interest rate?

As of early 2025, the late payment interest rate is 7.25%. This is charged daily on unpaid tax from 1 February (the day after the payment deadline) until the date you pay. Check HMRC's website for the current rate as it changes with Bank of England base rate movements.

Do I get penalised for late filing if I owe no tax?

Yes. The £100 late filing penalty is automatic and applies even if you owe no tax or are due a refund. The penalty is for failing to file, not for owing tax.

Can I appeal late filing and late payment penalties?

Yes. HMRC may cancel penalties if you have a reasonable excuse (serious illness, bereavement, HMRC system failure, etc.). You must file the return and pay the tax first, then appeal. See our guide on appealing HMRC penalties for the process.

Filed Your Tax Return Late? What Penalties and Interest Actually Cost You

You filed your Self Assessment late — or you’re about to. Now you want to know exactly what it’s going to cost you. This guide breaks down every penalty and interest charge with real numbers, so you can see the full picture and take action.

According to HMRC’s Self Assessment penalties guidance, there are two separate penalty regimes: one for late filing and one for late payment. They run independently, and you can be hit by both at the same time.

The Two Penalty Regimes: Filing vs Payment

Type	What it covers	When it starts
Late filing penalty	Failing to submit your tax return by 31 January	1 day after the deadline
Late payment interest + surcharge	Failing to pay your tax bill by 31 January	1 February (interest), 30 days late (surcharge)

You can be on time for one and late for the other. For example:

Filed on time, paid late → no filing penalty, but interest + late payment surcharges
Filed late, paid on time → filing penalties, but no late payment charges
Both late → the worst case — both sets of penalties apply

Let’s break down each one in detail.

Late Filing Penalties: The Full Scale

According to HMRC’s penalty rules, the late filing penalty escalates in four stages:

Stage 1: 1 day late — £100

An automatic £100 penalty is issued the day after the deadline. This applies regardless of:

Whether you owe tax
Whether you’re due a refund
Whether your tax bill is £0

This is the penalty that catches most people. It’s automatic and HMRC doesn’t need to contact you before issuing it.

Stage 2: 3 months late — £10 per day

After 3 months, HMRC adds a daily penalty of £10 per day for up to 90 days. That’s a maximum of £900 on top of the initial £100.

So at 3 months and 90 days late (approximately 6 months total), you’ve accumulated:

£100 (initial)
£900 (daily penalties)
Total: £1,000 in filing penalties alone

Stage 3: 6 months late — £300 or 5% of tax due

At 6 months, HMRC adds a further penalty of £300 or 5% of the tax due, whichever is higher.

If you owe £10,000 in tax, 5% = £500 — so you pay £500 (not £300).

Running total at 6 months:

£100 (initial)
£900 (daily penalties)
£500 (6-month penalty, if 5% of £10,000 > £300)
Total: £1,500 in filing penalties

Stage 4: 12 months late — £300 or 5% of tax due

At 12 months, another £300 or 5% of the tax due is added. If HMRC determines you deliberately failed to file, the penalty can be even higher — up to 100% of the tax due.

Running total at 12 months (owing £10,000):

£100 (initial)
£900 (daily penalties)
£500 (6-month penalty)
£500 (12-month penalty)
Total: £2,000 in filing penalties — on top of the £10,000 tax bill

Late Payment Interest: The Daily Clock

Separately from filing penalties, HMRC charges interest on any tax unpaid after 31 January.

The interest rate

The late payment interest rate is linked to the Bank of England base rate. As of early 2025, it’s 7.25%. HMRC reviews the rate regularly, so check HMRC’s current interest rates for the exact figure.

How interest is calculated

Interest is charged daily from 1 February until the date you pay. It’s simple interest, not compound.

For example, if you owe £5,000 and pay 60 days late:

£5,000 × 7.25% = £362.50 per year
£362.50 ÷ 365 = £0.99 per day
60 days × £0.99 = £59.59 in interest

If you pay 180 days late (6 months):

180 × £0.99 = £178.63 in interest

Interest applies to the tax, not the penalties

Importantly, interest is charged on the unpaid tax, not on the late filing penalties. So if you owe £5,000 in tax and have £1,000 in filing penalties, interest accrues only on the £5,000.

However, if you’ve been issued a late payment surcharge (see below) and don’t pay that, interest can accrue on the surcharge amount too.

Late Payment Surcharges: The 5% Charges

In addition to interest, HMRC applies late payment surcharges (also called “penalties” in some HMRC documentation) at three points:

When	Surcharge
30 days late (1 March)	5% of the tax unpaid
6 months late (31 July)	5% of the tax unpaid (additional)
12 months late (31 January next year)	5% of the tax unpaid (additional)

These are cumulative. If you owe £5,000 and haven’t paid after 12 months:

30-day surcharge: £5,000 × 5% = £250
6-month surcharge: £5,000 × 5% = £250
12-month surcharge: £5,000 × 5% = £250
Total surcharges: £750

Plus interest of approximately £362.50 (one year at 7.25%).

Real-World Example: The Full Cost of Filing and Paying Late

Let’s put it all together. Say you owe £8,000 in tax and you both file and pay 6 months late:

Filing penalties

Penalty	Amount
Initial £100	£100
Daily penalties (90 days × £10)	£900
6-month penalty (5% of £8,000 = £400, higher than £300)	£400
Subtotal	£1,400

Payment penalties

Penalty	Amount
30-day surcharge (5% of £8,000)	£400
6-month surcharge (5% of £8,000)	£400
Interest (180 days at 7.25%)	£287.67
Subtotal	£1,087.67

Grand total

Item	Amount
Original tax bill	£8,000.00
Filing penalties	£1,400.00
Payment penalties + interest	£1,087.67
Total owed	£10,487.67

That’s £2,487.67 in penalties and interest — a 31% increase on your original tax bill. And it gets worse the longer you wait.

What If You Filed on Time But Paid Late?

If you filed by 31 January but couldn’t pay your tax bill, you avoid all filing penalties. But you still face:

Interest from 1 February until you pay
Late payment surcharges at 30 days, 6 months, and 12 months

In this case, the best strategy is to pay as much as you can immediately to reduce the amount accruing interest, and contact HMRC about a Time to Pay arrangement for the remainder.

What If You Filed Late But Paid on Time?

If you paid your tax bill by 31 January but filed your return late, you face filing penalties only — no late payment interest or surcharges.

However, this is uncommon. Most people who file late also don’t know their exact tax liability, so they can’t pay on time. If you estimated your tax and paid by 31 January but filed late, you’ll face filing penalties but minimised your payment penalties.

How to Minimise the Damage Right Now

1. File immediately

Every day you delay past 3 months adds £10 to your penalty. File now via HMRC Online. See our guide on what to do if you missed the deadline for step-by-step instructions.

2. Pay what you can

If you can’t afford the full bill, pay as much as possible now. This reduces the amount accruing interest and the base for the 5% surcharges. Even a partial payment helps.

3. Set up a Time to Pay arrangement

If you owe less than £30,000, you can set up a payment plan online through your HMRC account. For larger amounts, you’ll need to call HMRC. See our Time to Pay guide for the full process.

4. Appeal if you have a reasonable excuse

If you had a genuine reason for filing or paying late (serious illness, bereavement, HMRC system failure), you may be able to get penalties cancelled. See our appeal guide for the process.

5. Don’t ignore it

The worst thing you can do is nothing. Penalties escalate, interest accrues, and HMRC can eventually take enforcement action — including sending debt collectors, using your tax code to collect the debt, or taking you to court. The earlier you act, the less it costs.

Payments on Account: An Extra Complication

If your tax bill is over £1,000, you’ll also be asked to make payments on account — advance payments toward next year’s tax bill. Each payment is 50% of your previous year’s tax bill, due on 31 January and 31 July.

If you filed late, your payments on account may not have been calculated correctly. When you do file, HMRC will recalculate them. This can mean your January payment is larger than expected because it includes:

Your balancing payment (last year’s tax minus what you’ve already paid)
Your first payment on account (50% of this year’s tax)

For a full explanation, see our MTD for income tax guide which covers how payments work under the new system.

The Bottom Line

Late filing and late payment penalties are designed to hurt — but they’re predictable. The key numbers to remember:

£100 — automatic filing penalty, 1 day late
£10/day — daily filing penalty, 3 months late (up to £900)
5% — late payment surcharge at 30 days, 6 months, and 12 months
7.25% — annual interest rate on unpaid tax (check current rate)

The strategy is simple: file and pay as soon as you can. Every day you wait costs money. If you have a reasonable excuse, appeal. If you can’t afford the bill, set up a payment plan. But don’t ignore it.

If you’ve missed the deadline entirely, see our emergency guide on what to do when you miss the Self Assessment deadline. If you can’t afford your tax bill, see what to do when you can’t afford your HMRC tax bill. To appeal a penalty, see how to appeal an HMRC penalty.

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