What Does Per Annum Pro Rata Mean
Understanding what does per annum pro rata mean in the UK workplace
Understanding "Per Annum Pro Rata"
"Per annum pro rata" combines two terms: "per annum" (Latin for "per year") and "pro rata" (Latin for "in proportion"). Together, they describe an annual salary figure that will be adjusted proportionally based on your actual working hours or pattern. It is the standard way UK employers advertise part-time salaries.
When you see "£28,000 per annum pro rata" on a job listing, this tells you the role pays £28,000 if worked full-time for a full year. Your actual annual pay will be a proportional fraction of this amount.
Decoding Job Advert Salary Phrases
| Phrase | What It Means | Your Actual Annual Pay (3 days/wk) |
|---|---|---|
| £28,000 per annum | Fixed annual salary | £28,000 |
| £28,000 per annum pro rata | FTE salary, adjusted for your hours | £16,800 |
| £28,000 FTE | Same as per annum pro rata | £16,800 |
| £16,800 actual salary | The real amount you'll receive | £16,800 |
Some employers helpfully show both: "£28,000 FTE (actual salary £16,800 for 22.5 hours)." Others only state the FTE figure, leaving you to calculate the actual amount.
Why Employers Use Per Annum Pro Rata
Employers state the full-time equivalent rather than the actual part-time salary because it enables fair comparison across roles. It also simplifies payroll administration — if an employee changes hours, only the ratio changes, not the underlying salary structure. This approach is mandated by many public sector pay scales (NHS Agenda for Change, teacher pay scales, civil service grades).
Use our pro rata calculator to convert any per annum pro rata figure to your actual salary. For definitions of related terms, see pro rata salary meaning or what is the pro rata salary.
Quick Summary: What Does Per Annum Pro Rata Mean
If you're short on time, here's what you need to know about what does per annum pro rata mean:
- What it means: What Does Per Annum Pro Rata Mean refers to proportional calculation based on the ratio of hours or time worked versus the full-time equivalent.
- The formula: Full-Time Amount × (Your Hours ÷ Full-Time Hours) = Your Pro Rata Amount
- Who needs it: Part-time workers, term-time staff, teachers, job-sharers, and anyone on reduced hours.
- UK law: Under the Part-time Workers Regulations 2000, part-time employees have the right to be treated no less favourably than comparable full-time workers.
Worked Example: What Does Per Annum Pro Rata Mean
Let's work through a practical example of what does per annum pro rata mean. A marketing coordinator role advertises a full-time salary of £28,000 for 37.5 hours per week. You're offered the position at 25 hours per week.
Step 1 — Find your FTE ratio: 25 ÷ 37.5 = 0.667 (66.7%)
Step 2 — Calculate pro rata salary: £28,000 × 0.667 = £18,667 per year
Step 3 — Monthly breakdown: £18,667 ÷ 12 = £1,556 gross per month
Step 4 — Holiday entitlement: 28 days × 0.667 = 18.7 days pro rata
After income tax and NI (2025/26 rates), your monthly take-home would be approximately £1,377. Use our pro rata calculator above to check your own figures.
Tips for What Does Per Annum Pro Rata Mean
- Always use gross salary: Enter the salary before tax and deductions — the calculator works with gross figures.
- Check your contract: Your employment contract should state your full-time equivalent hours. Common UK standards are 35, 37, 37.5, and 40 hours per week.
- Know your rights: Under the Part-time Workers Regulations 2000, part-time employees must receive the same hourly rate, holiday entitlement (pro rata), and benefits as full-time colleagues.
- Tax personal allowance: For 2025/26, the first £12,570 of earnings is tax-free. If your pro rata salary falls below this, you pay no income tax at all.
- National Insurance: Employee NI is 8% on earnings between £12,570 and £50,270 (2025/26 rates). Check HMRC NI rates for the latest figures.
Pro Rata Holiday Entitlement
Under the Working Time Regulations 1998, all UK workers are entitled to a minimum of 5.6 weeks' paid holiday per year (28 days for full-time). If you work part-time, your entitlement is calculated pro rata based on your actual hours or days worked.
| Days Worked/Week | FTE Ratio | Statutory Days/Year | Bank Holidays (pro rata) |
|---|---|---|---|
| 5 days (full-time) | 1.0 | 28 days | 8 days |
| 4 days/week | 0.8 | 22.4 days | 6.4 days |
| 3 days/week | 0.6 | 16.8 days | 4.8 days |
| 2.5 days/week | 0.5 | 14 days | 4 days |
| 2 days/week | 0.4 | 11.2 days | 3.2 days |
Holiday entitlement is always rounded up — never down — when the result is not a whole number, per ACAS guidance on holiday entitlement. Bank holidays may be included in or added on top of your statutory 28 days, depending on your contract.
All calculations on this page follow ACAS pro rata pay guidelines and are consistent with the UK Employment Rights Act 1996. Tax figures use HMRC 2025/26 rates. The April 2025 National Living Wage of £12.21/hour is applied where relevant.
Further Reading
For more help with what does per annum pro rata mean, explore our free UK tools. You may also find these useful: term-time salary calculator, overtime calculator, holiday pay guide.
Last updated: February 2026. Verified against HMRC 2025/26 tax rates and April 2025 National Living Wage (£12.21/hour).
Frequently Asked Questions
Pro rata means "in proportion." In employment, it refers to adjusting a full-time salary proportionally based on the number of hours, days, or weeks actually worked compared to a full-time equivalent role.
Divide the full-time salary by full-time hours, then multiply by your actual hours. For example: £30,000 ÷ 37.5 hours × 25 hours = £20,000 pro rata.
Pro rata salary is usually calculated before holiday pay. Your holiday entitlement is also pro-rated — part-time workers get 5.6 weeks holiday pro rata, calculated proportionally to hours worked.
Not exactly. Pro rata is the method used to calculate part-time salary. It ensures part-time workers receive the proportional equivalent of the full-time rate, maintaining fairness under UK employment law.