What Is an Income Tax Calculator?
A UK Income Tax calculator estimates how much Income Tax you'll pay for the selected tax year. It shows how your taxable income is split across tax bands and converts values into yearly, monthly, weekly, daily, and hourly figures so you can understand how tax affects take-home pay over different periods.
This tool focuses on Income Tax only — it does not include National Insurance, pension contributions, student loans or other deductions in the main calculations (unless added as "other taxable income"). It uses the numeric part of a tax code (for example, 1257L) to determine your personal allowance (digits × 10).
How to Use This Calculator
- Enter your gross salary before tax and deductions in the Gross Salary field.
- Select the Pay Period (Yearly, Monthly, Weekly, Daily or Hourly) for the amount you entered.
- Enter your Tax Code (e.g. 1257L). The tool will infer your personal allowance from it.
- If you have extra taxable income (rental, freelance, bonus), enter it in Other taxable income.
- Click Calculate to view the banded breakdown and periodised totals. Use the tabs to switch periods.
What the Result Shows
The results panel includes:
- Gross Pay — combined salary and other taxable income, annualised from your selected period.
- Personal Allowance — amount of tax-free pay inferred from your tax code.
- Taxable Pay — gross pay minus personal allowance.
- Tax per band — how much tax is charged at basic, higher and additional rates.
- Total Income Tax — the sum of tax across bands.
- Net after Income Tax — gross pay minus Income Tax (useful for quick checks).
- Effective Tax Rate — a percentage showing the overall tax burden relative to gross pay.
What Affects Your Income Tax?
Your Income Tax depends mainly on your total taxable income and your personal allowance. Other things that can change your tax bill include:
Tax Code
Your tax code tells HMRC how much tax-free income to give you. If your code changes (for example because of benefits, underpayments, or changes at HMRC), your tax will also change.
Multiple Incomes
If you have income from more than one source (second job, rental income), it increases your total taxable income and may push parts of your income into higher bands.
Pension Salary Sacrifice
Salary sacrifice reduces gross taxable pay in many schemes and lowers Income Tax. This calculator currently treats pension as external — you can reduce gross pay by editing your input to approximate sacrifice.
Scottish Tax
Scottish Income Tax bands are different. This tool uses UK standard bands. If you need Scottish-specific calculations, I can add a selector and rates.
Gross Pay vs Net Pay
Gross pay is the total you'll receive before Income Tax and other deductions. Net pay (for Income Tax) is gross pay minus Income Tax only. If you want a full take-home figure, use the take-home calculator which also includes National Insurance, pensions and student loan repayments.
Simple formula: Gross Pay - Income Tax = Net after Income Tax.
