How to split bills with your partner when you earn different amounts
Short answer
The two workable systems are 50/50 and proportional-to-income. Split 50/50 when your incomes are within roughly 20% of each other. When the gap is larger, split in proportion to income: add both take-home incomes, work out what percentage each of you contributes, and pay that percentage of every shared cost. Someone earning 65% of the household income pays 65% of the rent. It sounds clinical and it is the only method that leaves both people with a similar amount of discretionary money at the end of the month, which is what "fair" usually means in practice.
Key points
- Use take-home pay, not gross, and update it when either salary changes.
- Incomes within ~20%: split evenly, and spend the saved effort elsewhere.
- Proportional splitting equalises what is left over, not what goes out.
- The three-account system — yours, mine, ours — is the practical implementation.
- Whatever you pick, revisit it once a year. Most couples never do, and it silently stops fitting.
Why 50/50 stops being fair
Splitting evenly is fair when incomes are similar. When they are not, the same absolute amount takes very different bites. On take-home incomes of £4,000 and £2,000 with £2,000 of shared costs, £1,000 each leaves one person £3,000 of discretionary money and the other £1,000. They are contributing the same and living differently — and over a couple of years, that gap becomes a real difference in freedom, savings, and how often one of you says no to things.
Method 1: proportional to income
- 1
Add both take-home incomes
After tax and pension, since that is the money that actually pays bills. £4,000 + £2,000 = £6,000.
- 2
Work out each person’s percentage
4,000 ÷ 6,000 = 67%. 2,000 ÷ 6,000 = 33%.
- 3
Apply that to every shared cost
On £2,000 of shared costs: £1,340 and £660.
- 4
Check what is left
£2,660 and £1,340 of discretionary money. Still not equal — but proportionally identical, which is the goal.
| Earns £4,000 | Earns £2,000 | |
|---|---|---|
| 50/50 — contributes | £1,000 | £1,000 |
| 50/50 — left over | £3,000 | £1,000 |
| Proportional — contributes | £1,340 | £660 |
| Proportional — left over | £2,660 | £1,340 |
The lower earner is £340 a month better off under the proportional method — roughly £4,000 a year — while the higher earner still has twice as much left over. Nobody is subsidised; the burden is just carried in proportion to capacity.
Method 2: the three-account system
The practical way to run either split without a monthly conversation. Three accounts: yours, mine, and a joint one.
- 01Total your shared costs — rent, utilities, groceries, insurance, subscriptions, and a monthly slice of anything annual.
- 02Each of you sets up a standing order into the joint account for your agreed share, timed for payday.
- 03Every shared bill comes out of the joint account. Nobody pays anything shared from a personal account.
- 04Whatever is left in your own account is genuinely yours. No approval, no explanation, no ledger.
- 05Add a small buffer — one month of shared costs sitting in the joint account absorbs the month the boiler dies.
The reason this works is not the arithmetic — it is that it ends the running mental tally. Nobody is tracking who paid for the last shop, because the shop was paid by the joint account, which is nobody and both of you.
Method 3: split by category
One takes rent, the other takes groceries and utilities. It appeals because it is simple and requires no ongoing coordination.
It breaks quietly. Rent is fixed and groceries are not, so drift accumulates on one side. It also makes one person permanently responsible for the boring admin of variable bills. Use it only if the categories genuinely happen to match the ratio you want, and check it every six months.
Work out your proportional split
Enter your total shared monthly costs and set each person’s percentage.
Couple’s bill split calculator
Split shared costs between two people — evenly, or in proportion to what each of you earns.
Set each person’s percentage — useful for splitting in proportion to income.
Enter a shared monthly costs to see the split.
- You$0.00
- Partner$0.00
- Shared monthly costs
- $0.00
- Total
- $0.00
Household money, without the monthly spreadsheet.
FamZam keeps a shared ledger for the two of you — rent, groceries, subscriptions — and shows one clean balance at any moment.
The conversations worth having before you set this up
Do we use gross or take-home?
Take-home. Gross pay includes tax and pension contributions that never reach the bank. If one of you contributes far more to a pension, decide explicitly whether that counts as personal saving — it is a benefit accruing to one person, which is a fair thing to name rather than assume.
What counts as "shared"?
Rent, utilities, groceries, and household goods obviously. The arguments live at the edges: one person’s car used for both of you, a gym membership, a phone plan, a pet. Decide these as a list once. The list matters more than where you draw each line.
What about debt and dependants?
Student loans, child support, and family remittances come off the top before you calculate percentages, if you both agree they should. Someone earning £4,000 who sends £800 to family each month has £3,200 of real capacity, and treating it as £4,000 quietly makes them the lower earner in practice.
What happens if one of us stops earning?
Agree this while it is hypothetical, because it is the hardest conversation to start once it is real. Parental leave, redundancy, and a return to study all take a percentage to near zero. Proportional splitting handles it mathematically — 0% of the household income means 0% of the bills — and the point of agreeing early is that it stops feeling like a favour when it happens.
When do we review it?
Once a year, and after any raise, job change, or move. Put it in the calendar. The most common failure mode is not choosing the wrong system — it is choosing a good one and then leaving it in place three years after the incomes it was built on stopped existing.
Frequently asked questions
How should couples split bills when one earns more?
Split in proportion to take-home income. Add both incomes, work out each person’s percentage of the total, and pay that percentage of every shared cost. Someone earning 65% of the household income pays 65% of the rent. This leaves both people with a proportionally similar amount of discretionary money, which is usually what people mean by fair.
Is 50/50 fair if we earn different amounts?
It is fair when incomes are within roughly 20% of each other. Beyond that, the same absolute contribution takes a very different share of each person’s income, and the lower earner ends up with far less freedom despite contributing equally. The gap compounds over years into a real difference in savings.
What is the three-account system for couples?
Each partner keeps a personal account and both pay an agreed amount into a joint account by standing order on payday. Every shared bill is paid from the joint account, and whatever remains in a personal account is that person’s to spend without discussion. It works with either an even or a proportional split.
Should we use gross or take-home pay to calculate the split?
Take-home, after tax and pension, because that is the money that actually pays bills. If one of you contributes much more to a pension, decide explicitly whether that counts as personal saving — it is a benefit accruing to one person and worth naming rather than assuming.
How do you split bills if one partner stops working?
Under a proportional split it handles itself: a person with no income contributes 0% of shared costs. The important part is agreeing this before it happens — during parental leave, redundancy, or a return to study — so that it feels like a system working as designed rather than one person doing the other a favour.
How often should couples review how they split bills?
Once a year, and after any raise, job change, or move. The most common failure is not picking the wrong method but leaving a good one in place long after the incomes it was based on have changed.