How it works
Annual gross pay equals full-time salary × your hours ÷ full-time hours × your paid weeks ÷ full-time paid weeks. We calculate tax on each resulting annual salary separately, rather than reducing net pay by the same fraction. Monthly figures spread annual pay over 12 months.
Worked example
Worked example (2026/27): £30,000 full-time pay at 37.5 hours becomes £18,000 at 22.5 hours with the same paid weeks. In England with no pension or loan, that gives £16,479.60 net a year: £1,086 income tax and £434.40 National Insurance.
Assumptions
Uses the released 2026/27 annual PAYE model and one student-loan plan. Standard personal allowance, ordinary employee National Insurance, no bonus, taxable benefits, second job, Child Benefit charge or custom tax code. A steady annual salary is divided into pay periods; a payslip can differ because payroll thresholds and rounding apply each period. Pension tax-relief limits and minimum-wage eligibility for salary sacrifice are not assessed. This models a reduced-hours salary, not overtime or a mid-year start with earnings already received. Contractual pay and paid weeks must be checked with your employer.