How to split rent and bills with roommates

Sharing a flat means a steady trickle of small debts. One person pays the rent, another the internet, somebody else buys the washing-up liquid. Nobody minds any single one of them. What wears people down is not knowing, at the end of the month, who is actually up and who is down.

Here is a simple way to keep that straight — by hand if you like, or in OweMe, a free app for iPhone and Android that does the arithmetic for you.

1. Put every shared cost in one place

The rule that makes everything else work: every shared payment gets written down, by whoever made it, when they make it. Rent, bills, the big shop, the new kettle. A note on the fridge is fine for two people. For three or more, a shared record saves the arguments.

In OweMe that place is a group — "Flat 3B" — and everyone in the flat joins it from an invite link or a QR code. Each person has their own account, so nobody has to trust one person's spreadsheet.

2. Decide how each cost splits

Equal is right most of the time. When it is not, say so on the expense instead of working it out in your head:

• Equally — the internet, cleaning things, the shared shop.
• By shares — rent when the rooms differ. A couple in the big room counts as two shares, a single room as one.
• Exact amounts — when each person's part is already known, like a bill itemised per person.
• Percentages — for an agreed split such as 40 / 30 / 30.

When two people put money towards one bill, record both of them as payers on the same expense, rather than inventing one payer and a correction afterwards.

3. Set the rent once

Rent and bills repeat, so they should not need typing in every month. In OweMe you set an expense to repeat — daily, weekly, monthly or yearly — and it adds itself on the day. When the rent goes up, change the schedule. Going away for the summer, pause it. Rent due on the 31st stays on the 31st, even after February.

4. Look at one number per person, not a pile of IOUs

Every expense nets against every other one. If you paid the rent and your flatmate paid the electricity, those cancel out instead of becoming two debts to remember. What is left is one figure per person: how much they are up or down overall.

5. Settle up in as few payments as possible

When it is time to square up, everybody does not need to pay everybody. OweMe works out the fewest payments that clear the whole flat — often just one or two — and lists them. Here is how that works, with an example.

You pay each other however you already do: cash, a bank transfer, a favour returned. OweMe never touches money. Then tap Mark paid, and the person you paid confirms it, so a balance never moves on one person's word alone.

When someone moves out

They settle up first — a flatmate can leave the group once they are square — and everything they recorded stays in it under their name, so nobody else's balance changes when they go. The next flatmate joins from an invite link.

What it costs

Splitting a flat in OweMe is free, for good: all four ways of splitting, repeating expenses, the settle-up and invite links. The free plan covers three groups — a flatshare, a trip and a dinner club, say — with up to 300 expenses each and 90 days of history on screen. Older entries still count towards every balance; they are only hidden. Premium adds unlimited groups and history, offline use and a few other conveniences.