Ask PayslipIQ · Last reviewed 2026-05-08
Why is my tax so high this month?
There are three common causes. You were placed on an emergency tax code, you received a one-off payment that pushed you into a higher band for that period, or your tax code was updated mid-year. Compare your tax code on this month's payslip with last month's. If it changed, that is normally the cause.
PayslipIQ provides educational information and estimated calculations only. It does not provide tax, legal, financial, payroll, accounting, pension, benefits or employment advice. Always verify your payslip, tax code, deductions and take-home pay with your employer's payroll department, HMRC, your pension provider, a qualified accountant, tax adviser or another appropriately qualified professional.
HMRC issues tax codes per employee per employer. If your code changes from 1257L to BR or 0T mid-year, deductions can rise sharply.
Run your numbers through the free checker to see whether the tax taken matches your stated tax code. If it does not match, the most reliable next step is to log into your HMRC personal tax account and confirm what code HMRC has issued you.
Bonus pay is taxed at the marginal rate for that pay period, which can briefly push you into a higher band. The system corrects itself over the year if you are on a cumulative code, so the higher tax in one month often balances out across later months.
Related
Reviewed by PayslipIQ Editorial. Sources cited where applicable.
PayslipIQ provides educational information and estimated calculations only. It does not provide tax, legal, financial, payroll, accounting, pension, benefits or employment advice. Always verify your payslip, tax code, deductions and take-home pay with your employer's payroll department, HMRC, your pension provider, a qualified accountant, tax adviser or another appropriately qualified professional.