How to split bills fairly when you move in together

Moving in together is usually the easy part. The hard part shows up about six weeks later, when the internet bill is due, someone bought groceries again, and neither of you remembers who paid for what last time. Most money fights between couples aren't really about money — they're about not having a system, so every bill turns into a small negotiation.

You don't need a perfect formula. You need one you've both agreed to, so the default is "we already decided this" instead of "let's figure it out again."

Start with a conversation, not a spreadsheet

Before you pick a method, talk about two things: what counts as a shared expense, and whether you want strict fairness or rough fairness. Some couples want every dollar tracked. Others are fine with "it roughly evens out" and only settle up the big stuff. Neither is wrong — but you should each know which one you're doing, because mismatched expectations are what actually cause resentment.

Three ways couples usually split expenses

Even split. Rent, utilities, and groceries get divided 50/50, full stop. Simple to explain, easy to track, and it works well when your incomes are close. It gets tense when they're not — a 50/50 split feels very different to someone earning $2,800 a month than to someone earning $5,400.

Proportional split. Each person contributes based on income. If one of you earns 60% of the household's combined income, you cover 60% of shared costs. This is the one most couples land on once incomes diverge, because it keeps the split fair without either person tracking every transaction like an accountant.

Category split. Instead of splitting every bill, each person takes full ownership of certain categories — one of you covers rent and utilities, the other covers groceries and the streaming subscriptions nobody remembers signing up for. Works well when the categories land close to even, and it cuts down on the number of transactions you actually have to reconcile.

There's no rule that says you have to pick just one. Plenty of households do a proportional split for the big fixed costs (rent, utilities) and a category split for everything smaller.

Track what's shared, not everything

You don't need to log every coffee. What you need is a clear, boring way to mark which expenses are shared and which aren't, so "who owes who" is a fact you can check instead of a memory you're relying on. The moment tracking becomes about surveillance instead of a shared total, it stops working — the goal is one number you both trust, not a receipt-by-receipt audit of each other.

Settle up on a rhythm

Pick a cadence — weekly, every payday, or monthly — and settle up on it, even if the amount is small. Letting shared expenses pile up "until it's worth dealing with" is exactly how a fair system turns into a vague sense that someone's been paying more for months. A quick settle-up on a fixed schedule keeps the number from ever becoming a source of tension.

When incomes are very different

This is where a flat 50/50 split tends to break down. If one of you takes home $3,200 a month and the other takes home $5,100, an even split of a $2,400 rent means very different amounts of breathing room for each of you. A proportional split — roughly 39% and 61% of shared costs, matching the income ratio — keeps the burden actually even, even though the dollar amounts aren't.

The exact percentage isn't the point. The point is picking something that reflects your real situation rather than defaulting to "even" because it's the easiest number to say out loud.

Whatever method you land on, the thing that actually keeps it working long-term is having one shared view of what's been spent, what's shared, and what you owe each other — instead of two separate mental tallies that quietly drift apart. That's the whole idea behind Nido.