PAYE salary estimates can look wrong when the tax code is wrong or incomplete. The tax code tells payroll how much tax-free allowance to apply and whether special adjustments are needed.
This guide is general information. It is not HMRC advice, payroll advice or tax advice. Check your personal tax account, payslip and employer payroll team before relying on a result.
A tax code changes the allowance applied through payroll
A common code such as 1257L generally points to the standard Personal Allowance, but individual circumstances can change the code.
Benefits in kind, underpaid tax from a previous year, multiple jobs or pension income can reduce or change the allowance applied to one job.
UK rates can differ by nation and income type
Income Tax rates and bands can differ for Scottish taxpayers. Welsh rates also have their own administration, and PAYE coding should reflect the correct position.
A simple salary calculator may assume England, Wales or Northern Ireland bands unless it specifically asks for a Scottish tax basis.
Examples that often explain a payslip difference
Example 1: A worker on 1257L and another on a reduced code can have different tax on the same salary.
Example 2: A company car or medical benefit can change the code and reduce monthly take-home pay.
Example 3: A second job can receive a BR, D0 or other code, so the pay from that job may be taxed differently.
Included and excluded items
- Included: Gross salary, Standard Personal Allowance assumption, Basic, higher and additional rate bands where applicable, PAYE-style monthly or annual estimate
- Not included: Your exact HMRC tax code notice, Benefits in kind, Student loan plans, Scottish-specific full modelling unless entered, Previous-year underpayments
- Check before relying on the result: HMRC personal tax account, Payslip tax code, Employer payroll team, GOV.UK Income Tax rates