Calculate your income tax, National Insurance, student loans, pension tax relief, and fuel duty. See exactly how much tax you pay on petrol, diesel, and heating oil with live UK government fuel price data.
Tax year 2025/2026 rates: This calculator uses the latest UK income tax and National Insurance thresholds. Your personal allowance reduces by £1 for every £2 you earn over £100,000.
Pension tax relief: With "Relief at Source", basic rate tax relief is added to your pension automatically. Higher and additional rate taxpayers can claim extra relief through self-assessment. With "Net Pay", contributions are deducted before tax.
Student loans: Repayments are based on your income above the threshold for your plan type. Plan 1, 2, and 4 charge 9% above threshold; Postgraduate loans charge 6%.
Tax Codes: Your tax code tells your employer how much tax-free income you're entitled to. A wrong code could mean under or over-paying tax. Check your latest payslip or P60.
High Income Child Benefit Charge: If you or your partner earn over £50,000, you may have to pay back some or all of your Child Benefit through tax. Between £50,000 and £60,000, this creates an effective marginal tax rate of over 60% - one of the highest in the UK tax system!
Effective Tax Rate: The average percentage of your total income that goes to tax. Calculated as: (Total Tax Paid ÷ Gross Income) × 100. This includes Income Tax, National Insurance, Student Loan repayments, and Child Benefit charges.
Marginal Tax Rate: The tax rate applied to your next pound of income. This is crucial for understanding how much of a pay rise you'll actually keep. For example, if your marginal rate is 42% (higher rate taxpayer), a £1,000 bonus means £420 in tax and only £580 in your pocket. Watch out for the 60%+ trap between £50,000-£60,000 with Child Benefit!
Fuel Duty & VAT: Fuel duty is a flat rate per litre charged on petrol and diesel (52.95p/L as of 2025/26). VAT at 20% is then applied to the total of the fuel cost plus duty - meaning you pay tax on the tax! This results in over 50% of the pump price being tax for road fuels. Heating oil (kerosene) has a reduced fuel duty rate and 5% VAT for domestic use.
UK Fuel Prices: Our fuel price data comes directly from the UK government's Weekly Road Fuel Prices dataset, which tracks average pump prices across the country. The data is updated weekly and embedded in our calculator at build time for instant access.
This calculator is for informational purposes only and does not constitute financial advice.