How to Split Bills When You Earn Different Amounts
Four ways couples split shared costs, what each one does to the person earning less, and how to choose between them. With the arithmetic shown.
There are four sensible ways to split shared costs, and which is fairest depends on the size of the gap between your incomes and how much is left after the essentials are paid. Equal, proportional, equal remainder and residual. Most couples default to the first without ever choosing it, then find out years later that it was quietly costing one of them everything they had left.
This is the arithmetic, with the same numbers run through all four so you can see what each does.
The example
Two people. One takes home £3,600 a month, the other £2,400. Shared costs, meaning rent, bills, food and everything the household consumes rather than either person, come to £2,400.
Nothing here depends on who earns which. The pattern is the same whichever way round it is.
1. Equal: straight down the middle
£1,200 each.
What it leaves them with: £2,400 and £1,200.
Simple, and fair when incomes are close. At this gap it is doing something people rarely intend. The higher earner keeps twice as much personal money as the lower earner, so every discretionary decision in the household, from holidays to whether a broken washing machine gets repaired or replaced, is now made by one person by default. Not because anyone decided that, but because only one of them has the money to say yes.
Equal splitting is the honest choice when the gap is small. It stops being neutral somewhere around a 60/40 income split, and nobody notices the crossing.
2. Proportional: each pays their share of the income
The higher earner brings 60% of the household income and pays 60% of the costs.
£1,440 and £960.
What it leaves them with: £2,160 and £1,440.
This is the one most people mean when they say "fair". The ratio of what is left matches the ratio of what came in, so nobody is subsidising anybody, and the person earning less is not paying a larger fraction of their life for the same roof.
It is the default in EvenUS, and there is a longer walk through the maths in income proportional bill splitting and calculating fair financial splits.
3. Equal remainder: protect a personal allowance first
Each person keeps a fixed amount for themselves before anything is shared. Say £600 each.
That leaves £3,000 and £1,800 to cover £2,400 of costs, split in proportion to what is left: £1,500 and £900.
What it leaves them with: £2,100 and £1,500.
The point is the protected floor. Both people have money that is theirs, that nobody has to be told about, and that does not have to be justified. For a household where one person earns much less or nothing at all, this is often the difference between a partnership and an allowance.
4. Residual: both end up with the same
Split so that after shared costs, both have an identical amount left.
Total income £6,000, minus £2,400 of costs, leaves £3,600 to divide evenly: £1,800 each. So the higher earner pays £1,800 and the lower earner pays £600.
What it leaves them with: £1,800 and £1,800.
This is the most equalising and the least popular, and both of those are worth taking seriously. It works well when finances are genuinely merged and the couple thinks of the money as one pot. It grates when they do not, because the higher earner can feel that earning more changed nothing about their own life, and that resentment is as corrosive as the imbalance it was meant to fix.
All four, side by side
| Method | Higher earner pays | Lower earner pays | Left over |
|---|---|---|---|
| Equal | £1,200 | £1,200 | £2,400 / £1,200 |
| Proportional | £1,440 | £960 | £2,160 / £1,440 |
| Equal remainder | £1,500 | £900 | £2,100 / £1,500 |
| Residual | £1,800 | £600 | £1,800 / £1,800 |
Every row is defensible. The failure is not picking the wrong one, it is never picking at all, which means picking Equal without noticing.
Which should we use?
Look at what is left, not at what is paid. That single change settles most of the argument, because "we both pay half" and "one of us has nothing left" can be true at the same time and only the second one is felt.
A rough guide:
- Incomes within about 15% of each other: Equal is fine and simplest.
- A real gap, both comfortable: Proportional.
- A real gap and the lower earner is tight: Equal remainder, so there is a protected floor.
- Fully merged finances, shared long-term goals: Residual.
And revisit it. A method chosen when you both earned similar amounts is not a decision that survives a promotion, a redundancy or a year of parental leave. Rebalancing after a job loss or promotion covers what to change and when.
What about unpaid work?
Do not convert it into money. This is a deliberate position rather than an oversight.
The temptation is obvious. One partner does most of the housework, so price it at some hourly rate and credit it against their share of the bills. It looks like justice and it goes wrong quickly. It requires agreeing a rate for your partner's time, which is a conversation nobody enjoys having twice. It makes every task a transaction. And it quietly says that unpaid work matters because of what it would cost to buy, which is not why it matters.
Measure both, keep them separate. Money on one axis, time and mental load on the other. A household can be fair on money and badly unfair on time, and averaging the two into one number hides exactly the thing worth seeing. That is why the mental load is tracked on its own, and why fair does not always mean equal.
Do we need a joint account?
No. The method matters, the plumbing does not. All four splits work with entirely separate accounts and a standing order into a shared pot, or with one joint account, or with an app and a monthly settle-up.
What does matter is that both people can see the whole picture. Not visibility of each other's personal spending, which is surveillance, but agreement on what the shared costs are and what each is contributing to them. Managing household finances without a joint account and yours, mine and ours go through the structures.
The conversation, not the spreadsheet
Most money arguments between couples are not about money. They are about one person feeling that a decision was made without them, or that they have to ask permission to spend on themselves. The split is worth getting right because it removes the cause, not because the arithmetic is interesting.
Two things make the conversation easier. Do it on a day when nothing is due, because a discussion about method held while a bill is overdue becomes a discussion about the bill. And write down what you chose, including why, so that in eighteen months you are revisiting a decision rather than relitigating one.
Financial transparency covers what to share and what does not need sharing, and red flags in couple finances covers the point where this stops being an arrangement problem.
Running it on your own numbers
EvenUS does this calculation continuously rather than once. You set the method, it tracks what each of you actually paid against what the method says you should have, and it shows the gap without telling either of you what it means about you. Money stays on its own axis, and hours are never priced.
The calculator on the homepage runs proportional splitting on whatever numbers you put in, and income aware splits shows the calculation the app runs behind it.