An extra afternoon each week can be worth more than another salary increment. It can also be unaffordable. The decision needs both a price for the time and a check that the remaining income can support the household.
Here the choice is changing hours in the same job, rather than moving to a new employer or adding overtime.
Price a four-day proposal
Illustrative 2026–27 scenario: an employee in England, Wales or Northern Ireland moves from £40,000 for five days to £32,000 for four, with pay reduced exactly in proportion to days. Assume standard allowance, category A NI, equal monthly pay, no student loan, no other income and no pension deduction for this initial comparison. Pension and benefit terms need checking separately.
Using HMRC Income Tax rates, annual tax is £5,486 at £40,000 and £3,886 at £32,000. Using monthly NI thresholds, annualised employee NI is approximately £2,193.92 and £1,553.92. Unrounded monthly calculations are used; payroll can differ by pennies.
Cash after these deductions is £32,320.08 versus £26,560.08. The £8,000 gross reduction costs £5,760 of net cash a year, or £480 a month—not the £666.67 gross monthly difference.
Subtract only costs that really stop
Assume the missing workday removes £12 travel and £4 incremental food spending for 46 working weeks. That saves £16 × 46 = £736. The net annual cash cost of the change becomes £5,024, or about £418.67 a month.
If the released day represents eight hours including travel, it creates 368 hours across those 46 weeks. The cash trade-off is about £13.65 per hour released. That does not put a market price on family time or imply the hours can be sold. It makes the cost visible.
A childcare saving belongs in the calculation only if the arrangement and bill actually reduce. A season ticket already purchased may not fall in proportion to days. An employer pension contribution might fall, and retirement value belongs beside the immediate cash result.
Check that the day genuinely becomes free
A four-day contract with five days of work squeezed into evenings is a different offer. Clarify workload, targets, availability, holiday treatment and who covers the missing day. Otherwise the household could pay £418.67 a month for time it never receives.
GOV.UK's flexible-working guidance explains the statutory right to request flexible working. A right to request is not a guarantee that a particular arrangement will be accepted. Northern Ireland has separate guidance; check the rules relevant to your employment.
Make the household test explicit
If the current genuine monthly margin is £600, the example change leaves about £181.33 before pension or other differences. If it is £300, the change creates a shortfall unless another reliable adjustment is made. The same time benefit can therefore lead to different sensible decisions.
Possible alternatives include a trial arrangement, a smaller hours reduction or changes to travel days. Agree the terms rather than assuming all flexibility costs the same.
The most useful answer may be “yes, with this workload and this budget”, or “not yet, because this commitment ends next year”. Both are more informative than deciding that time is priceless and then discovering the rent still expects a number.
