What is a Pro-Rata Salary?
A pro-rata salary is a proportionally adjusted annual pay figure that reflects the actual hours or days you work compared to a full-time equivalent (FTE) contract. The phrase comes from the Latin pro rata parte, meaning "according to the calculated share." It is the standard method used by UK employers to calculate pay for part-time workers, those on reduced-hours contracts, or employees who start or leave mid-year.
For example, if the full-time equivalent salary for a role is £36,000 per year based on a 37.5-hour week, and you work 25 hours per week, your pro-rata salary would be £24,000 per year — exactly two-thirds of the full-time figure, reflecting your two-thirds working week.
The Pro-Rata Formula
There are two common methods for calculating pro-rata pay in the UK:
Method 1: By Hours Per Week
Example: £30,000 ÷ 37.5 × 22.5 = £18,000 pro-rata
Method 2: By Days Per Week
Example: £30,000 ÷ 5 × 3 = £18,000 pro-rata
Both methods produce the same result when hours-per-day are consistent. Our calculator supports both approaches — simply toggle between Hours per Week and Days per Week mode above.
How UK Tax Applies to Pro-Rata Salaries
Your pro-rata salary is taxed under the standard UK PAYE system — the same rules that apply to full-time salaries. The key advantage of working part-time is that you retain your full £12,570 Personal Allowance for the 2026/27 tax year under the standard tax code 1257L. This means a much larger proportion of your lower pro-rata salary is sheltered from Income Tax compared to a full-time wage.
Income Tax Bands (England, Wales & Northern Ireland — 2026/27)
| Band | Taxable Income | Rate |
|---|---|---|
| Personal Allowance | Up to £12,570 | 0% |
| Basic Rate | £12,571 – £50,270 | 20% |
| Higher Rate | £50,271 – £125,140 | 40% |
| Additional Rate | Over £125,140 | 45% |
National Insurance Contributions (2026/27)
Class 1 NI applies to earnings above the Primary Threshold of £12,570. On pro-rata salaries below this threshold, no NI is payable at all — a significant saving for low-hours workers.
| Earnings Band | NI Rate |
|---|---|
| Up to £12,570 (Primary Threshold) | 0% |
| £12,571 – £50,270 (Upper Earnings Limit) | 8% |
| Above £50,270 | 2% |
Holiday Entitlement on Pro-Rata Contracts
Under the Working Time Regulations 1998, part-time workers are legally entitled to the same annual leave as full-time employees, calculated on a pro-rata basis. The statutory minimum is 28 days per year (5.6 weeks, including 8 public bank holidays) for someone working 5 days a week.
To calculate your pro-rata holiday entitlement: 28 × (Actual Days Per Week ÷ 5). A 3-day week gives 16.8 days; a 4-day week gives 22.4 days. Our calculator automatically shows your entitlement in the results panel.
Pension Auto-Enrolment on Part-Time Salaries
Workplace pension auto-enrolment applies if you are aged 22 or over, earn above £10,000 per year, and are classed as a worker. The minimum contribution under auto-enrolment is 5% employee + 3% employer on qualifying earnings (£6,240 – £50,270 for 2026/27).
Note that pension contributions are deducted from your gross salary before Income Tax is calculated (for relief-at-source schemes), reducing your taxable income and therefore your Income Tax bill. Use the Pension Contribution field in our calculator to see the precise impact on your take-home pay.
Pro-Rata & Furlough FAQs
What does pro-rata salary mean in the UK?
Pro-rata means "in proportion" (from Latin). A pro-rata salary scales a full-time annual salary down to reflect the actual hours or days worked. For example, a full-time role paying £36,000 for 37.5 hours/week would pay £18,000 pro-rata on a 18.75-hour contract.
How is pro-rata pay calculated?
Pro-Rata Salary = (Full-Time Annual Salary ÷ Full-Time Hours Per Week) × Actual Hours Per Week. Alternatively by days: (Full-Time Salary ÷ Full-Time Days Per Week) × Actual Days Per Week. The resulting figure is then taxed exactly like any other UK salary under PAYE rules.
Do I still get the full Personal Allowance on a pro-rata salary?
Yes. Your £12,570 Personal Allowance (tax code 1257L) applies regardless of whether you work full-time or part-time. This means lower pro-rata salaries often attract proportionally less Income Tax than a full-time equivalent.
How is holiday entitlement calculated on a pro-rata basis?
Part-time workers are entitled to the same annual leave as full-time staff, calculated pro-rata. The UK statutory minimum is 28 days (including 8 bank holidays) for full-time. A 3-day week (60%) gives 16.8 days. Our calculator shows your entitlement automatically.
Does National Insurance apply to pro-rata salaries?
Yes. Class 1 National Insurance applies to pro-rata earnings above the Primary Threshold (£12,570 in 2026/27) at 8%, and 2% above the Upper Earnings Limit (£50,270). Many part-time workers on low pro-rata salaries pay little or no NI.
How is pension calculated on a pro-rata contract?
Workplace pension auto-enrolment applies if you earn above £10,000 per year. Contributions are typically 5% employee and 3% employer on qualifying earnings (between £6,240 and £50,270). Our calculator lets you enter your specific contribution rate to see the impact on take-home pay.
