Shared expenses4 min read

How to split household expenses with your partner without it becoming a thing

Three ways to divide shared costs — down the middle, proportional to income, and a common pot — when each one fits, and how to track it without a spreadsheet.

September 1, 2026

Living with someone and sharing expenses has a part nobody warns you about: the hard bit isn't agreeing on how to split, it's keeping the agreement alive for months. You start with the best intentions, open a spreadsheet, and three weeks later only one of you is updating it. What's left is the feeling — on both sides, and almost always unfair — that one of you put in more.

Below are the three approaches people actually use, with the case each one fits and the problem each one brings. There's no correct answer: there's one that survives in your situation.

1. Down the middle

Every shared expense is split in half. It's the simplest, which is exactly why it works best when both incomes are similar.

When it fits: similar incomes, or when what matters most is that the rule be so obvious there's nothing to argue about.

The problem: if one of you earns twice as much, halves aren't equality — they're the opposite. Whoever earns less ends up putting a far bigger share of their income toward the same things, and that asymmetry piles up quietly until it surfaces one day in an argument that seemed to be about something else.

2. Proportional to income

Each person contributes according to what they earn. If you make 60 and the other person makes 40, shared expenses split 60/40.

When it fits: when incomes differ a lot and you both want the effort to weigh about the same on each of you, rather than the number to be identical.

The problem: the percentages have to be recalculated every time an income changes. It also requires an explicit conversation about how much each of you earns, which is easy in some couples and not in others.

A middle ground that works well: set the percentages once, with round numbers, and revisit them twice a year instead of every month.

3. A common pot

You both put a fixed amount into a shared pool every month and everything shared comes out of it. Whatever stays outside the pot is yours and isn't accounted for.

When it fits: when you want to stop tracking expense by expense. It asks for the least day-to-day administration.

The problem: the amount has to be calibrated, and the first two or three months it's almost always short or over. Large irregular expenses — a move, a broken fridge — break the scheme and have to be settled separately anyway.

What makes any of the three work

The method matters less than it seems. What decides whether the agreement survives is something else:

Both of you see the same thing, without asking. The precise point where these accounts get abandoned is when one person is the one "keeping the spreadsheet" and the other asks. It stops being an agreement and becomes a favour.
Fixed expenses log themselves. Rent and utilities repeat every month: if someone has to remember to write them down, sooner or later they don't.
Settling up is a moment, not a reconstruction. If squaring up at the end of the month means re-reading the chat to see who paid what, it won't happen.

How Kesef handles it

You create a group with whoever you share expenses with, and each of you logs what you pay for. The balance recalculates whenever either of you adds something and you both see it at the same time: there's no spreadsheet that one person updates.

Fixed expenses — rent, service charges, utilities — can be left as recurring, so they show up without anyone remembering.

And each expense is split however suits you, chosen per expense rather than once for the whole group:

Evenly, which between two people is 50/50.
By percentage, for the proportional-to-income split: 60/40, 70/30, whatever you agreed.
By shares, when one of you has the big bedroom or someone ate for two.
By exact amounts, for when the split follows no rule at all.

With that, all three approaches above fit without forcing anything: halves is even, proportional is the percentage, and for a common pot it's enough to log the contributions. And because you choose per expense, rent can go 60/40 while last night's dinner goes evenly, inside the same group.

The last part, which is what you notice most over time: your share reaches your own monthly summary — not the full amount you fronted, and not zero. And settling a debt counts as neither expense nor income, so the month you square up doesn't look like a month of income that never existed.

Groups and recurring expenses are on the free plan, for both of you.