Late Tax Penalty calculator

Calculate late filing fines and interest from HMRC..

Tax Year

1. Your Situation

Filing deadline for 2026-2027: 31 January 2028

⏳ Tax year not yet over

The 2026-2027 tax year runs until 5 April 2027. You cannot file a return for this year yet — the filing deadline is 31 January 2028. There are no penalties to calculate right now.

2. Results

✓ You're fine.

The current tax year isn't over yet. The deadline is 31 January 2028. There are no penalties or interest to pay right now.

* Based on HMRC Self Assessment penalty rules. HMRC interest rate used: 8.00% p.a. (BoE base rate + 4%, effective 6 April 2025). Actual amounts may differ — consult HMRC or a tax adviser for your specific situation.

How does the Late Tax Penalty work?

Identify the deadline for your tax return (usually Jan 31st).

Calculate the number of days past the deadline.

Apply the initial £100 fixed penalty for being even 1 day late.

After 3 months, add the daily £10 penalties.

After 6 and 12 months, add the percentage-based penalties (5% of tax due).

Smart Calculations

Calculated instantly with up-to-date HMRC thresholds. Our engine ensures 100% accuracy for the current tax year.

Pro Tip: Keep your receipts!

What makes you liable?

Time is Money: Penalties escalate quickly, especially after the 3-month mark.

Reasonable Excuse: HMRC may waive penalties if you have a valid reason for the delay (e.g., serious illness).

Interest: In addition to penalties, HMRC charges interest on any unpaid tax from the deadline date.

Get your tax sorted with TaxSimba

You've calculated your estimate. Now choose the right service and we'll guide you through the next steps with expert, accountant-led support.

Self Assessment
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How it works

Get started in a few simple steps.

Choose your package

Select Self Assessment or MTD and pick the right plan for you.

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Late Tax Penalty calculator

1. Your Situation

2. Results

How does the Late Tax Penalty work?

Smart Calculations

What makes you liable?

Get your tax sorted with TaxSimba

Self AssessmentTax Return

Making Tax Digital(MTD) Packages

How it works

Choose your package

Create your account

Secure payment

We'll take care of the rest

Late Tax Penalty calculator

1. Your Situation

2. Results

How does the Late Tax Penalty work?

Smart Calculations

What makes you liable?

Get your tax sorted with TaxSimba

Self AssessmentTax Return

Making Tax Digital(MTD) Packages

How it works

Choose your package

Create your account

Secure payment

We'll take care of the rest

Self Assessment
Tax Return

Making Tax Digital
(MTD) Packages

Self Assessment
Tax Return

Making Tax Digital
(MTD) Packages