Self assessment tax return calculator

Use our free self-assessment tax return calculator to estimate how much tax you owe (or should have paid) for a tax year. This is an estimate, not a substitute for HMRC’s official calculation.

Get your tax return paid directly to HMRC, and spread the cost monthly, keeping money in your business.

This calculator is intended for illustration purposes only and exact payment terms should be agreed with a lender before taking out a loan.

Your results

Total earnings

Tax to pay

£ income tax
£ class 2 National Insurance
£ class 4 National Insurance

You're left with

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Who needs to use a Self Assessment tax calculator?

You may need to complete a self-assessment tax return if you:

Are self-employed or a sole trader
Work as a freelancer or contractor
Earn rental income from property
Receive dividends or other untaxed income
Have income over £100,000
Need to declare foreign income

A self-assessment calculator is especially useful if your income varies throughout the year.

How a self-assessment tax return calculator works

Our UK self-assessment calculator estimates your tax in a few simple steps:

Adds up your total income
Deducts allowable business expenses
Applies the Personal Allowance
Calculates Income Tax based on current tax bands
Adds Class 2 and Class 4 National Insurance (if self-employed)

The result is an estimated tax bill you can use to plan ahead.

What taxes are included in the calculation?

A good Self Assessment tax return calculator will usually include:

Income Tax (basic, higher, and additional rates)
Class 2 National Insurance
Class 4 National Insurance

Some calculators also allow for pension contributions and Gift Aid donations, which can reduce the amount of tax you pay.

Self-assessment deadlines to remember

31 October – Paper tax return deadline
31 January – Online tax return and tax payment deadline
31 July – Second payment on account (if applicable)

Missing these deadlines can result in penalties and interest.

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