Four-Day Week and Take-Home Pay: 2026/27 UK Guide
How a four-day week affects your UK take-home pay in 2026/27. Pro-rata salary, tax, National Insurance and pension impacts explained with worked examples.
Quick answer
A four-day week changes your take-home pay only if your salary is cut pro-rata. Under the 100-80-100 model you keep full pay for four days, so nothing changes. Under a pro-rata cut your gross drops by roughly a fifth, but your net falls by a little less, because Income Tax and National Insurance also fall. Model both figures in the
Take-Home Pay Calculator
Calculate your net salary after income tax, National Insurance and student loan deductions.
Open Take-Home Pay calculatorTwo very different four-day weeks
The phrase "four-day week" hides two arrangements with opposite effects on your wallet. Getting the distinction right is the whole game.
The 100-80-100 model
This is the version that dominated the headlines from the large UK trials. You work 80% of your previous hours -- four days instead of five, or the equivalent compressed pattern -- while keeping 100% of your pay, in return for maintaining 100% of your output. Financially, nothing about your payslip changes. Your gross salary, Income Tax, National Insurance, pension contributions and any student loan deductions stay exactly as they were. The benefit is purely the extra day of time.
The pro-rata reduced-hours model
Here you genuinely move to four days and your salary is reduced in proportion. A 20% cut in days usually means a 20% cut in gross pay. This is where the tax mechanics get interesting, because while your gross falls by a flat fifth, your take-home falls by less than a fifth.
Why a pro-rata cut hurts less than it looks
UK Income Tax and National Insurance are progressive. You pay nothing on the first GBP 12,570 (the Personal Allowance), then 20% up to GBP 50,270, then 40% above that to GBP 125,140. Employee National Insurance is 8% between GBP 12,570 and GBP 50,270, then 2% above. Because the top slices of your income carry the highest marginal rates, removing a slice of gross pay removes the most heavily taxed pounds first.
The practical result: when you give up a day's pay, you give up pounds that were being taxed at your highest marginal rate. The taxman effectively shares the cost of your day off with you.
Worked example: a higher-rate earner
Take someone on GBP 60,000 moving to a true four-day week at GBP 48,000 (a 20% gross cut of GBP 12,000).
| Item | GBP 60,000 (5 days) | GBP 48,000 (4 days) | Change |
|---|---|---|---|
| Gross salary | 60,000 | 48,000 | -12,000 |
| Personal Allowance | 12,570 | 12,570 | unchanged |
| Taxed at 20% | 37,700 | 35,430 | -2,270 |
| Taxed at 40% | 9,730 | 0 | -9,730 |
| Income Tax | 11,432 | 7,086 | -4,346 |
| Employee NI (8% / 2%) | 3,212 | 2,834 | -378 |
In this case the GBP 12,000 gross cut removes the entire chunk that was in the 40% band plus a slice of the 20% band. The Income Tax bill falls by GBP 4,346 and NI by GBP 378, so the actual hit to take-home is far smaller than GBP 12,000. The exact figure depends on your pension, student loan plan and any benefits in kind, so always confirm with the
Take-Home Pay Calculator
Calculate your net salary after income tax, National Insurance and student loan deductions.
Open Take-Home Pay calculatorWorked example: a basic-rate earner
For someone on GBP 30,000 moving to GBP 24,000, every pound of the GBP 6,000 cut was taxed at 20% with 8% NI. The combined marginal rate of 28% means roughly GBP 1,680 of the cut is borne by reduced tax and NI, so the take-home reduction is around GBP 4,320 rather than the full GBP 6,000. The effect is real but smaller than for the higher-rate earner, because there is no 40% slice to fall out of.
A higher-rate earner crossing back below GBP 50,270 benefits most from a pro-rata cut, because the top pounds were taxed at 40% plus 2% NI. A basic-rate earner sees a steadier 28% combined relief on the slice given up. The closer your cut sits to a band boundary, the more the maths works in your favour.
Scotland is different
If you are a Scottish taxpayer, the bands and rates differ. Scotland runs Starter 19%, Basic 20%, Intermediate 21%, Higher 42%, Advanced 45% and Top 48% rates. The principle is identical -- a pro-rata cut removes your most heavily taxed pounds first -- but because Scotland has more bands and steeper higher rates, the cushioning effect of a pay cut can be even more pronounced for higher earners. National Insurance is set UK-wide, so the 8% and 2% rates apply the same way north of the border.
What else moves with a pro-rata salary
A four-day pay cut does not stop at Income Tax and NI. Several other figures flex with your gross:
- Pension contributions. If yours are a percentage of salary, the cash paid in falls proportionally. Over decades that compounds into a meaningfully smaller pot. The GBP 60,000 Annual Allowance is rarely the binding constraint at reduced salaries.
- Student loan repayments. These are 9% of income above your plan threshold (or 6% above GBP 21,000 for Postgraduate loans). Lower pay means lower repayments, and if a cut takes you below the threshold, repayments pause. See the to model this.ƒTry the calculator
Student Loan Repayment Calculator
Calculate monthly student loan repayments for Plans 1, 2, 4 and 5.
Open Student Loan calculator - Salary-linked benefits. Maternity pay, sick pay reference periods, life cover and bonus calculations may all be based on your reduced salary going forward.
- State Pension qualifying years. As long as earnings stay above the Lower Earnings Limit you keep building entitlement towards the GBP 241.30 weekly full new State Pension. Drop too low and you may need voluntary Class 3 contributions at GBP 18.40 per week to fill a gap.
Should you soften the cut with salary sacrifice?
If you are taking a pro-rata cut but can afford it, redirecting some of what remains into a pension via salary sacrifice is tax-efficient: contributions come out before Income Tax and National Insurance. You trade a little more take-home now for a bigger, tax-relieved pot later. Two guardrails apply. First, the Annual Allowance is GBP 60,000. Second, sacrifice cannot push your pay below the National Living Wage, which is GBP 12.71 per hour for workers aged 21 and over. Run the numbers on the
Pension Calculator
Estimate your pension pot at retirement and projected annual income.
Open Pension calculatorHow to model your own four-day week
The cleanest method takes two minutes:
- Enter your current full-time salary in the and note the monthly net.ƒTry the calculator
Take-Home Pay Calculator
Calculate your net salary after income tax, National Insurance and student loan deductions.
Open Take-Home Pay calculator - Calculate your pro-rata figure -- for a five-to-four move, multiply by 0.8, or use the to convert to a daily rate first.ƒTry the calculator
Salary Converter
Convert between hourly, daily, weekly, monthly and annual salary.
Open Salary Converter calculator - Enter the reduced salary and compare the two net figures.
- The monthly difference is the genuine cost of your extra day off. Divide by four to see what each free Friday actually costs.
Many people are surprised to find the real cost is noticeably less than 20% of net, especially if they were sitting in the higher-rate band. That gap is the tax system quietly subsidising your shorter week.
The bottom line
A four-day week is a take-home pay event only when it comes with a salary cut. If you keep full pay under a 100-80-100 deal, your payslip is untouched and you simply gain time. If your salary is reduced pro-rata, the headline cut overstates the pain: progressive Income Tax and National Insurance mean your net falls by less than your gross, with higher-rate earners cushioned most. Before you accept any offer, model both salaries side by side in a take-home pay calculator and check the knock-on effects on pension, student loan and State Pension. The right number is rarely the one in the headline.
Frequently asked questions
Does a four-day week always cut my take-home pay?
Not always. The popular 100-80-100 model keeps full pay for four days, so your take-home is unchanged. The pay only falls if your employer reduces salary pro-rata for the lost day. In a pro-rata cut your gross drops by around a fifth, but tax and National Insurance also fall, so your net pay drops by slightly less than the headline salary cut because some income shifts out of the higher-tax bands.
How much tax do I save if my salary is cut for a four-day week?
You keep your GBP 12,570 Personal Allowance regardless of hours, so a lower salary is taxed at the same band rates on less income. If the cut pushes part of your pay out of the 40% higher-rate band into the 20% basic band, the saving on that slice doubles in your favour. Use a take-home pay calculator to model your exact figure, since the saving depends on where your salary sits in the bands.
Will my pension contributions fall on a four-day week?
If contributions are a percentage of salary and your salary is cut pro-rata, the cash amount paid in falls proportionally, which reduces your long-term pot. The Annual Allowance of GBP 60,000 is rarely the constraint at lower salaries. Auto-enrolment minimums still apply on qualifying earnings. If pay is unchanged under a 100-80-100 model, your pension contributions are unaffected.
Does National Insurance change if I work four days?
Employee Class 1 NI is 8% on earnings between GBP 12,570 and GBP 50,270 and 2% above that. A pro-rata salary cut reduces the earnings on which 8% is charged, so your NI bill falls. If the cut moves income below GBP 50,270, you lose the small 2% band advantage on that slice but pay 8% on less overall. Net pay still rises relative to the gross cut because NI scales with earnings.
Is a four-day week the same as part-time work for tax?
For tax purposes there is no special status. HMRC taxes your actual earnings, whether you work four days or five. A compressed four-day week on full pay is taxed exactly like a five-day role. A reduced-hours four-day week is taxed like any other lower salary. Your Personal Allowance, bands and NI thresholds are annual figures and do not change with the number of days worked.
How does a four-day week affect student loan repayments?
Student loan repayments are 9% of income above your plan threshold (GBP 25,000 on Plan 5, GBP 29,385 on Plan 2, GBP 26,900 on Plan 1) or 6% above GBP 21,000 for Postgraduate loans. A lower pro-rata salary reduces the income above the threshold, so your monthly repayment falls. If a pay cut takes you below the threshold entirely, repayments stop until your earnings recover.
Can I keep full pay on a four-day week?
Yes, under the 100-80-100 model many employers keep salaries at 100% for 80% of the hours, in exchange for maintaining 100% productivity. This is the arrangement trialled in several large UK pilots. Where this applies, your gross pay, tax, National Insurance and pension are all unchanged. The change is to your working pattern only, not your finances.
Should I salary-sacrifice to soften a four-day pay cut?
Salary sacrifice for pension can reduce the sting of a smaller pay packet because contributions come out before tax and National Insurance. You give up some take-home now but build retirement savings tax-efficiently. The Annual Allowance is GBP 60,000. Sacrifice cannot take your pay below the National Living Wage of GBP 12.71 per hour for those aged 21 and over. Model the trade-off before committing.
Does a four-day week affect my State Pension?
The new State Pension full rate is GBP 241.30 per week for 2026/27, based on National Insurance qualifying years, not hours. As long as your earnings on a four-day week stay above the Lower Earnings Limit, you continue to build qualifying years. If reduced pay drops you below the limit, you may get a gap year, which you can later fill with voluntary Class 3 contributions at GBP 18.40 per week.
Which calculator should I use to plan a four-day week?
Start with a take-home pay calculator: enter your current salary, then enter the pro-rata reduced figure, and compare the net results side by side. The difference is the real cost of the extra day off. A salary calculator helps you convert annual pay to a daily or weekly rate, and a National Insurance calculator isolates the NI element if you want to see each deduction separately.
Try the calculators
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