Understanding your UK payslip: gross pay, PAYE, NI and deductions
A salary calculator starts with annual figures. A payslip is a payroll record for one pay period. Understanding the difference makes it much easier to diagnose why an online estimate and an actual month may not match exactly.
Gross pay and taxable pay
Gross pay is the amount before deductions. Taxable pay can differ because some payroll items reduce taxable earnings while taxable benefits or adjustments can increase the amount PAYE operates on.
PAYE Income Tax
PAYE uses your tax code and payroll basis to collect Income Tax during the year. A standard 1257L code broadly reflects the £12,570 standard Personal Allowance, but your code can be different because of benefits, underpayments, allowances or HMRC adjustments.
National Insurance
Employee Class 1 National Insurance is normally calculated independently for each pay period. That is one reason a large bonus month can behave differently from a smooth annual estimate.
Student loans and pensions
Student-loan deductions use pay-period thresholds. Pension deductions depend on the scheme: salary sacrifice, net pay and relief-at-source arrangements are not interchangeable. Netly Pay currently models salary sacrifice because it is useful for scenario planning.
When to investigate a difference
If the difference is material, check your tax code, taxable pay year-to-date, pension method, student-loan plan and whether you had bonuses or benefits. HMRC and your payroll team are the authoritative route for an individual PAYE issue.
A five-step payslip check
- Confirm the pay period, gross contractual pay and any overtime or bonus.
- Check the tax code shown against the code you expect HMRC to have issued.
- Separate taxable pay from amounts that may be treated differently, such as qualifying salary sacrifice.
- Check NI and student-loan deductions against the correct pay-period thresholds rather than an annual average alone.
- Compare year-to-date taxable pay and tax with earlier payslips if something changed unexpectedly.
A new job, bonus, benefits adjustment or emergency tax code can make one month's PAYE look unusual. Netly Pay is useful as a reasonableness check, but your employer's payroll record and HMRC tax code determine the actual deduction.
When to contact someone
Ask payroll first if the gross pay, pension contribution or deduction basis looks wrong. For a tax-code issue, HMRC is normally the authoritative source. For student-loan plan details, check your Student Loans Company information and GOV.UK guidance.