75/25 split bills: a practical guide (UK)

A 75/25 split is a strong version of “pay more if you earn more”. It can be a good fit when incomes are very different, but you still want the lower earner to have a comfortable leftover and a realistic savings rate.

Last updated: 2025-12-17

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Methodology

Try a 75/25 split in the calculator

Opens the main calculator prefilled so you can compare 75/25 vs proportional vs 50/50 — and check stress tests.

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When 75/25 makes sense

75/25 is usually a choice about outcomes. If you’re aiming for similar leftovers (or similar savings), a bigger split can be reasonable even if it isn’t exactly proportional. It can also make budgeting calmer: instead of constantly recalculating ratios, you agree a fixed rule and revisit it at milestones.

The downside is drift. If salaries change, 75/25 may stop matching affordability. That’s why it’s important to re‑run the numbers and the stress tests — budgeting guidance only, not financial advice.

Worked examples (with numbers)

Each example below is a shareable scenario. Open it to adjust rate, term, deposit, and costs.

Example 1: very different incomes, same home plan

Incomes: A £5,200 / B £1,700 · Home £410,000 · Deposit 10%

Total shared cost: £2,947 / month

Proportional

A £2,221 · B £726

50 / 50

A £1,474 · B £1,474

Selected: 75 / 25 · Leftovers: A £2,990 / B £963

Open this scenario in the calculator See 70/30 examples

Example 2: higher split used to keep both saving

Incomes: A £4,100 / B £2,400 · Home £525,000 · Deposit £95,000

Total shared cost: £3,583 / month

Proportional

A £2,260 · B £1,323

50 / 50

A £1,791 · B £1,791

Selected: 75 / 25 · Leftovers: A £1,413 / B £1,504

Open this scenario in the calculator See 70/30 examples

A simple decision checklist

After the split, does each person have a leftover they can live on (and ideally save from)?
Does the household still look okay at +1% and +2% mortgage rates?
If one income drops temporarily, could the other person cover the shared cost for a month or two?
Have you agreed what costs are shared (including whether groceries are shared)?

FAQ

Is 75/25 too extreme?

It depends on your incomes and goals. A large split can be fair if one person earns much more, if you’re protecting one person’s savings, or if you’re reflecting other responsibilities. Validate it with leftovers and stress tests.

Does 75/25 mean we don’t have equal say?

A split is about affordability and sustainability, not control. Many couples keep decisions 50/50 while contributions differ.

Should the higher earner pay 75% of everything, including groceries?

Not necessarily. Some people prefer fixed bills proportional but day‑to‑day spending (groceries, eating out) more equal, because it feels simpler and avoids resentment.

How often should we revisit the split?

A practical rule is every 6–12 months, or after a job change / childcare change. Re‑run +1% / +2% and one‑income checks each time.