Pro Rata Pay for Starters and Leavers

Two denominators that do not agree

Pro rata pay is a fraction times an annual salary, and the fraction is only as honest as its denominator. A calendar method uses 365 days, or 366 in a leap year. A working-day method might use 260 days after weekends are removed, or 261 if the employer counts a different set of public holidays. Take £36,000. One day on the calendar method is £36,000 divided by 365, which is £98.63. One day on a 260-day method is £138.46. Calculators King editors recommend writing the denominator next to the annual salary before anyone multiplies, because a silent switch from 365 to 260 changes a single day by £39.83.

Hours are a third denominator. A full-time week of 37.5 hours across 52 weeks is 1,950 hours, so one hour of a £36,000 salary is £18.46 before tax. A contract that quotes 35 hours and 52 weeks uses 1,820 hours and prices the hour at £19.78. Those two hourly rates differ by £1.32, and a 70-hour starter month then differs by £92.40. Prefer the hour count printed in the contract over a generic 40-hour week. The result is educational and not personal, legal, or clinical advice, so match it to the employer's own divisor before you treat a stub payslip as short.

A starter who joins on 1 October

A non-leap year gives October, November, and December 92 days. Calendar pro rata for a £36,000 salary is 92 divided by 365, times 36,000, which comes to £9,073.97. If payroll instead counts 65 working days left out of 260, the same salary pays 65 divided by 260, times 36,000, which is exactly £9,000. The gap is £73.97 before tax, National Insurance, or pension. Do not reuse either figure as a January daily rate without rebuilding the fraction. We recommend showing both stubs to the new starter when the offer is silent, because £73.97 is large enough to look like a missing day.

Bank holidays inside the stub need a rule of their own. If 25 December and 26 December are paid days off, a working-day count that already excluded them must not exclude them again. Counting 65 days and then deleting two holidays produces 63 and a stub of £8,723.08, which is £276.92 below the £9,000 figure. That second cut is a double removal, not a stricter pro rata. Ask payroll whether public holidays are inside the 260 or outside it, and keep the answer with the offer letter. Recompute the stub from salary, days worked, and the divisor only.

A leaver whose last day is 14 March

From 1 January through 14 March is 31 plus 28 plus 14, which is 73 days in a non-leap year. Calendar pro rata on £36,000 is 73 divided by 365, times 36,000, or £7,200 exactly. A working-day story can land on the same cash by accident: 52 days out of 260 is also 52 divided by 260, times 36,000, or £7,200. The match is a coincidence of these two counts, not a law. Move the last day to 20 March and the calendar count becomes 79 days, or £7,791.78. Record the last paid day, not the date on the resignation email.

Notice periods create a second date. Someone who resigns on 1 March and works until 14 March is paid through the 14th, not through the 1st. Using 60 days instead of 73 values the leaver at £5,917.81, which is £1,282.19 short of £7,200. Holiday not taken is often a separate line, paid at a daily rate that may use yet another divisor. We recommend a three-line leaver note: last paid day, divisor, and accrued leave in hours. The result is educational and not personal, legal, or clinical advice. A solicitor or the employer's payroll manual decides what the contract actually requires when those lines disagree.

Part-time fractions on the same stub

A 0.8 contract on a £33,333 full-time salary is £26,666.40 a year before the stub is applied. October's 65 working days out of 260 then pay £26,666.40 times 65 divided by 260, which is £6,666.60. Multiplying in the other order, stub first, gives the same product because both steps are straight multipliers: £33,333 times 65 divided by 260 is £8,333.25, and 0.8 of that is also £6,666.60. Rounding is where the order starts to matter. If someone rounds the part-time salary to £26,666 and only then applies 65 over 260, the stub becomes £6,666.50, ten pence lower.

Ten pence is small once. It is not small if the same rounding hits 12 monthly stubs and a leaver payment. Twelve months at a penny error is only £0.12, but a ten-pence monthly slip is £1.20 a year, and a one-pound rounding of the annual part-time salary moves the October stub by about £0.25. Prefer to keep two decimal places until the final payslip line. Calculators King editors recommend writing the full-time salary, the full-time hours, the actual hours, and the day fraction on one row. The result is educational and not personal, legal, or clinical advice, and it will not know if a local agreement rounds each month.

Name the method in the offer

An offer that says only "pro rata" has not chosen a denominator. Add one sentence: calendar days over 365, working days over 260, or hours over 1,950. For the £36,000 starter on 1 October, those choices produced £9,073.97, £9,000, and a third figure once hours replace days. Put the worked stub in the letter as an example, including the pence. Future readers can then audit a payslip without guessing which public holidays were inside the 260. If the employer uses 261 days in some years because the weekday pattern shifts, say that the divisor is the payroll calendar for that leave year, not a permanent 260.

Leavers need the same sentence. State whether unused leave is paid on the same divisor as salary. A 3.5-day leave balance on the £138.46 working-day rate is £484.61, while the same 3.5 days on the £98.63 calendar rate is £345.21. The difference is £139.40, which is larger than the £73.97 starter gap that opened this article. We recommend agreeing the leave rate before the last week, when there is still time to correct a roster. Keep the calculation educational: it is not personal, legal, or clinical advice, and the signed contract remains the document payroll will follow.

Match three numbers on the payslip

When the stub arrives, check salary, fraction, and cash, not the cash alone. For the working-day October example the payslip should support £36,000, 65 over 260, and £9,000. If the cash is £8,723.08, look for a 63-day fraction before you assume tax caused the gap. Tax and pension can remove £1,000 or more from a gross stub, but they do not change the gross fraction printed above them. A gross of £9,000 and a net of £7,400 can both be right. A gross of £8,723.08 against a promised 65-day fraction cannot, until someone explains the two missing days.

Store the offer, the day count, and the payslip in one folder for the first three months. If January then uses a fresh annual fraction, recompute it instead of dividing £9,000 by three and calling that a month. A later leaver calculation should start from the annual salary again, not from a rounded monthly gross. Calculators King editors recommend re-running the fraction whenever the last paid day changes by even one date. The result is educational and not personal, legal, or clinical advice. If the gross still disagrees, ask payroll for the divisor in writing before you escalate.

Open the worksheet

The matching page is the Pro Rata Salary Calculator. It opens with a worked example, names the formula, and keeps the steps next to the result. Use it when you want the arithmetic on your own numbers rather than the argument on this page.