UK Pro-Rata Salary Calculator
Work out a part-time salary from a full-time equivalent (FTE). Enter the full-time figure plus your hours, days, or FTE % — we'll show pro-rated income tax, NI, student loan, and pension so you see take-home side-by-side against full-time.
Pro-Rated Annual Salary
£36,000
30 / 37.5 hours per week (80% FTE)
Pro-Rated Take-Home (annual)
£29,440
£2,453 / month
Net vs FT Net
81.96%
Gross ratio: 80.00%
| Item | Full-Time | Pro-Rated | Difference |
|---|---|---|---|
| Gross Salary | £45,000 | £36,000 | -£9,000 |
| Income Tax | £6,486 | £4,686 | -£1,800 |
| National Insurance | £2,594 | £1,874 | -£720 |
| Student Loan | £0 | £0 | £0 |
| Pension | £0 | £0 | £0 |
| Take-Home Pay (annual) | £35,920 | £29,440 | -£6,480 |
| Monthly Take-Home | £2,993 | £2,453 | -£540 |
| Weekly Take-Home | £691 | £566 | -£125 |
Why pro-rata net ≠ pro-rata gross
Personal Allowance is flat
Everyone gets the first £12,570 tax-free. A part-time salary uses a bigger proportion of this allowance, pulling your effective tax rate down.
Progressive bands
Going part-time can drop you out of the 40% higher-rate or 60% effective band (where PA tapers). Net can fall by much less than 20–30%.
NI primary threshold
NI isn't charged until £12,570. A low-FTE part-time role can be under the threshold entirely — zero employee NI.
Student loan thresholds
Plan 1/2/4/5 all have their own thresholds. Pro-rated income may fall under the threshold for plans with high cut-offs (Plan 4 at £31,395), saving 9% of the excess.
Frequently asked questions
How do I calculate a pro-rata salary?
Pro-rata salary = full-time equivalent (FTE) salary × your FTE ratio. If a job advertises £40,000 FTE and you'll work 30 hours against a 37.5-hour full-time week, your FTE is 30/37.5 = 0.8 (80%), so your pro-rata salary is £40,000 × 0.8 = £32,000.
Does pro-rata affect my tax and take-home pay?
Yes, but not proportionally. Because UK income tax is progressive and everyone gets the same £12,570 Personal Allowance, a part-time salary is taxed at lower average rates than the full-time equivalent. Your net pay usually falls by less than your gross salary in percentage terms.
What counts as full-time hours in the UK?
There is no statutory UK definition, but 35 to 40 hours per week is typical, with 37.5 hours being the most common for office-based roles. Check your employer's standard full-time hours when calculating your FTE ratio — NHS Agenda for Change uses 37.5, many law firms use 35, and retail often uses 40.
Should pension contribution percentage stay the same when going part-time?
Usually yes — most workplace pensions apply the contribution as a percentage of your actual (pro-rated) salary. So a 5% contribution still means 5%, but the cash amount scales down with your salary.
Does going part-time change my National Insurance?
Employee NI has a £12,570/year primary threshold — you only pay NI on earnings above that. If your pro-rated salary falls below the threshold (or close to it), you may pay little or no NI despite earning a meaningful salary.