Going Part-Time: The Real Cost of Four Days
You give up 20% of gross and around 16% of take-home. Whether that is a good trade depends on numbers most people never work out.
Dropping a day costs 20% of gross and consistently less than 20% of take-home, because the Personal Allowance stays whole while the most heavily taxed slice of your income disappears first. The higher your salary, the better that trade looks.
In a tiered pension scheme the effect is larger again, because fewer hours can move you into a lower contribution tier.
What each fraction costs
| Full-time salary | On four days | Net loss a month | % of net given up |
|---|---|---|---|
| £28,000 | £22,400 | £336.00 | 17.0% |
| £35,000 | £28,000 | £420.00 | 17.5% |
| £45,000 | £36,000 | £540.00 | 18.0% |
| £60,000 | £48,000 | £606.49 | 16.0% |
| £85,000 | £68,000 | £821.67 | 16.5% |
| £115,000 | £92,000 | £861.67 | 13.9% |
Against what you buy with the day
The comparison most people are actually making is against childcare. A nursery day at £70 is about £300 a month, which at many salaries is close to what the fifth day nets you. Add the travel you no longer do and the two numbers converge further.
What does not appear in the arithmetic: pension accrual falls, and in most organisations progression slows. Those are real and they are the reason to think about it rather than just calculate it. The NHS page and the teaching page have the public sector versions.
Questions people actually ask
How much less do you take home on four days?
Does part-time affect my pension?
The numbers this sits on
| Salary | Income tax | National Insurance | Take-home | A month | Effective rate |
|---|---|---|---|---|---|
| £25,000 | £2,486 | £994 | £21,520 | £1,793 | 13.9% |
| £35,000 | £4,486 | £1,794 | £28,720 | £2,393 | 17.9% |
| £45,000 | £6,486 | £2,594 | £35,920 | £2,993 | 20.2% |
| £60,000 | £11,432 | £3,210 | £45,358 | £3,780 | 24.4% |
| £85,000 | £21,432 | £3,710 | £59,858 | £4,988 | 29.6% |
| £110,000 | £33,432 | £4,210 | £72,358 | £6,030 | 34.2% |
Every figure in that table is computed from the published 2026/27 rates by the same engine that runs the calculators on this site, so a number in an article and a number in a calculator can never drift apart. National Insurance uses the statutory period thresholds real payroll uses, which is why these figures reconcile with a payslip rather than nearly reconciling with one.
| Salary | England, Wales, NI | Scotland | With a Plan 2 loan | Keep from the next £1,000 |
|---|---|---|---|---|
| £28,000 | 28.0% | 28.0% | 28.0% | £720.00 |
| £40,000 | 28.0% | 29.0% | 37.6% | £720.00 |
| £52,000 | 42.0% | 44.0% | 51.6% | £580.00 |
| £65,000 | 42.0% | 44.0% | 50.4% | £580.00 |
| £105,000 | 62.0% | 69.5% | 70.4% | £380.00 |
| £130,000 | 47.0% | 50.0% | 56.6% | £530.00 |
Work it out for yourself
- Take-home pay calculatorThe main calculator, all four UK nations.
- Pay rise calculatorWhat a raise really adds.
- Salary sacrificeWhat you are trading.
- Tax code checkerWhat each letter and prefix does.
Figures on this page are for the 2026/27 tax year (6 April 2026 to 5 April 2027) and were last checked on 29 August 2026. Every rate we use is listed on the sources page.