Updated for 2026/27 · No signup · Estimate only, not financial advice
The fastest way to check is to compare your payslip's tax code, gross pay, and deductions against what they should be for your income using our free Payslip Checker — it flags common errors like an incorrect tax code or missed pension relief in seconds.
What to check first
Tax code — the standard 2026/27 code is 1257L. An emergency code (like 1257L W1/M1) or a BR/D0 code (common with second jobs) can mean you're paying too much or too little.
National Insurance category — most employees are category A. Anything else should match your specific circumstances (e.g. state pension age, apprentice).
Pension contributions — check the percentage matches what you agreed with your employer, and that tax relief has been applied correctly.
Worked example
On a £35,000 salary with a standard 1257L tax code, you should pay roughly £309/month Income Tax and £220/month National Insurance. If your payslip shows a noticeably different figure, check your tax code first — it's the most common cause of payslip errors.
An incorrect or emergency tax code is by far the most common cause of a wrong payslip, often after starting a new job or changing circumstances without HMRC being informed in time.
How do I fix an incorrect tax code?
Contact HMRC directly, or ask your employer to check the tax code they've been given. Once corrected, any overpaid tax is usually refunded automatically through your pay.
Why is my National Insurance different to last month?
NI is calculated per pay period, not as an annual average, so it can vary slightly if your pay varies — for example with bonuses, overtime, or a change in hours.