Dropping to four days, taking a term-time contract, or agreeing a percentage pay arrangement? Enter the full-time salary and how your working pattern changes — reduced hours, a straight percentage, or weeks worked per year — and see the pro-rata gross with a complete 2026/27 take-home breakdown, side by side with the full-time position.
5 min read·Updated 17 July 2026·🇬🇧 UK
Calculator
Full-Time Position
£
Scottish taxpayer
New Working Pattern
Reduced hours
% of pay
Weeks / year
%
Deductions
None
Sacrifice
Net Pay
Relief at Source
Full-time vs pro-rata
Monthly take-home compared
Your result
Enter your details above to see your personalised result.
How it works
How pro-rata pay is calculated
A pro-rata salary is the full-time-equivalent (FTE) salary scaled by the fraction of full-time work you actually do. Three common arrangements, all supported here:
Reduced hours — new hours ÷ full-time hours. 30 of 37.5 hours = 80% of salary.
Percentage of pay — a direct agreement, e.g. 60% pay on a job share.
Weeks worked — term-time and seasonal contracts, e.g. 39 of 52 weeks = 75%.
The interesting part is what happens after tax. Because the personal allowance is fixed, cutting your gross cuts only the top slice of taxed income — so take-home always falls by a smaller percentage than gross. That asymmetry is exactly what this page quantifies, using the same 2026/27 engine as the rest of the suite.
Worked example: four-day week on £35,000
Four days is 80% of a five-day pattern, so the pro-rata gross is £28,000. Full-time take-home is about £28,720 a year; at £28,000 gross it becomes roughly £23,680. You give up 20% of gross but only about 17.5% of net — the day off costs around £420 a month in take-home. Many people find that number surprisingly affordable; now you can check it for your own salary.
Divide your new weekly hours by the full-time hours and multiply the full-time salary by that fraction. A £35,000 full-time role at 37.5 hours becomes £28,000 at 30 hours (30 ÷ 37.5 = 0.8). This calculator then runs the full 2026/27 tax and NI calculation on the pro-rata figure.
Why does part-time take-home fall by less than the pay cut?
Because tax is progressive: the hours you give up were your most heavily taxed pounds. Dropping from £35,000 to £28,000 cuts gross by 20%, but take-home falls only around 17% because the lost income was all taxed at 20% plus 8% NI, while your personal allowance stays intact.
Does going part-time affect my personal allowance or tax code?
No — the £12,570 personal allowance is yours regardless of hours. Your tax code stays the same and PAYE simply deducts less. The allowance becomes a bigger share of a smaller salary, which is why part-time work is comparatively tax-efficient.
How is holiday entitlement pro-rated?
The statutory minimum of 5.6 weeks applies pro-rata: at 3 days a week you accrue 16.8 days instead of 28. This calculator handles pay; check your contract for how your employer rounds part-time holiday.
Can I model term-time or reduced-weeks working?
Yes — choose the weeks-worked mode and enter how many weeks a year you are paid for. A term-time contract of 39 weeks on a £30,000 full-time-equivalent produces a pro-rata gross of £22,500, and the calculator shows the tax and NI on that figure.
Do pension contributions change when I go part-time?
Percentage-based contributions scale automatically with your lower pay, and employer contributions usually scale the same way. Watch qualifying-earnings schemes: the £6,240 lower band is fixed, so it removes a proportionally larger slice of a part-time salary from pension calculations.
Disclaimer: Figures are estimates based on current rates and rules. Tax legislation may change. Verify with HMRC or consult a qualified accountant before making financial decisions based on these figures.