Write a Money Agreement Before You Move In Together

The lease is sitting in your inbox with a signature box at the bottom. You've agreed on the flat with the better kitchen, you've agreed on the first weekend of the month, and neither of you has said a word about whose name goes on the account that pays for it. That's normal. It's also exactly why a financial agreement before moving in together is worth two hours of one Sunday: right now you both want to be generous with each other, and generous is the easiest state in which to write something precise.

Money is not a random topic to pick. Dew, Britt and Huston's 2012 study in Family Relations ("Examining the Relationship Between Financial Issues and Divorce") found that financial disagreements predicted divorce more strongly than disagreements about chores, in-laws, or sex, for both husbands and wives. Not because couples are greedy. Because money arguments are recurring, they have a paper trail, and each one reactivates every previous one.

What follows are the five mistakes that turn a happy move into a two-year argument, worst first. Some of this is legal and binding. Some of it is just a document that stops the two of you remembering the same conversation differently, which is most of the value.

Mistake 1: Signing the lease before you've agreed what happens if one of you moves out

This is the most expensive mistake on the list, because the lease is the one document here that a court will enforce whether or not you discussed it. Most joint residential tenancies make each tenant liable for the whole rent, not half of it. UK government guidance on tenancy types and Shelter England both spell this out: in a joint tenancy you are jointly and severally liable, so the landlord can pursue either of you for the full amount. Standard US leases say the same thing in the phrase "jointly and severally liable."

Here's how it goes wrong. Say Priya and Tom sign a twelve-month joint tenancy at $2,400 a month. In month five it ends. Tom moves out on a Saturday and stops paying, assuming he's out of it. He isn't. Priya either finds $2,400 a month out of one income or the landlord chases them both, and Tom's credit gets a mark on it he didn't expect. If Tom's mother signed as guarantor, she is on the hook for the whole rent too, not for Tom's share.

The sole-name version is just as bad in the other direction. If only one of you is on the lease, the other has no right to stay in the home, no claim on the deposit, and can be asked to leave with fairly short notice, no matter how many months of rent they've contributed.

It's tempting to skip because raising "what if we split up" while signing a lease feels like cursing the thing before it starts. And the letting agent wants the forms back by Friday. But the conversation takes twenty minutes and you will never have a better time to have it than a week before you own the problem.

What to write down instead:

• Notice. Whoever is leaving gives the other written notice. Sixty days is a good number, because it matches most landlords' re-let timelines.
• Who keeps paying, and until when. For example: the person leaving pays their share of rent and utilities until a replacement tenant is approved by the landlord or the notice period ends, whichever comes first.
• Who does the work. Finding the replacement, showing the flat, dealing with the agent. Name the person, not "we both".
• Who keeps the tenancy. Decide now. "If we separate, Priya stays and Tom is released" is a real answer. "We'll see" is not.
• The legal reality. Write, in plain words, that only the landlord can remove someone from the lease, and that until they do it in writing (a deed of surrender, a new tenancy, a signed amendment), both of you remain liable no matter what you've agreed privately. This sentence prevents a specific, common shock.

Mistake 2: Merging everything into one pot, or splitting everything 50/50, when your incomes aren't equal

The fix is a three-account structure with a percentage attached to it, not a vibe about fairness. Yours, mine, ours: two personal accounts that nobody has to justify, and one joint account funded by a standing transfer two days after each payday that covers rent, utilities, groceries, insurance, and a named buffer.

The 50/50 default is where the slow resentment lives. Take net monthly take-home of $3,200 and $5,100. Shared costs of $2,400. Split evenly, each pays $1,200, which leaves one of you with $2,000 to live on and the other with $3,900. One person is choosing between a haircut and a train ticket home while the other books a weekend away. Split proportionally, at 38.5% and 61.5%, and it's $924 and $1,476, leaving $2,276 and $3,624. Still not identical. Considerably less corrosive.

Proportional isn't automatically right. It depends on whether you're treating your finances as one household economy or two adults sharing a roof. If one of you has $40,000 of student debt and the other has none, or one is supporting a parent, write those numbers into the calculation instead of pretending the take-home figure tells the whole story. What matters is that the percentage exists on paper and both of you can say where it came from.

The all-in-one-account version fails differently. Every $60 dinner becomes visible and therefore discussable, and within a year one of you is saying some version of "I don't mind that you bought the boots, I mind that I found out about them from the app." So set an explicit no-questions threshold. Something like: anything under $200 from your own personal account needs no explanation, ever, and anything over $200 that comes out of joint money gets mentioned first.

A few specifics worth writing in:

• Exact transfer amounts and dates. "Tom transfers $1,476 on the 3rd, Priya transfers $924 on the 26th." Not "we each put in our share."
• A buffer, with a number. One month of shared costs sitting in the joint account. Agree who tops it up if it gets used.
• Whose debt is whose. Default: personal debt is paid from personal money. If you're deviating from that, say so in a sentence.
• Joint account risk. Either holder can empty a joint account and both are liable for an overdraft. Which is a good reason for the joint account to hold one month of costs and a buffer, not your savings.

Mistake 3: Nobody records who paid the deposit or who bought the sofa

Write the deposit and every shared purchase over $250 into one shared list with the date, the item, who paid, and what happens to it if you separate. Do it the week you move in, because after that nobody remembers and both of you will remember it in your own favour.

The deposit is the classic. Say one of you pays the $2,400 deposit plus the first month because the other's bonus hasn't landed, with a cheerful "sort me out later." Later doesn't have a date on it. Eighteen months on, one of you is certain it was squared up against a holiday and the other is certain it wasn't. Then the tenancy ends, the landlord returns the deposit to the lead tenant's account, and now there's a real sum of money sitting in one person's bank with two stories attached to it.

So write the rule: the deposit is repaid to whoever put it in, in full, before anything is split. Deductions for damage come off the deposit and are shared, unless one of you clearly caused it, in which case say how you'll decide that (a photo, a repair invoice).

For furniture, agree a buyout formula so you're not negotiating in the worst week of your relationship. One that works: the person keeping the item pays the other 50% of the original price, reduced by 20% for each year owned. Your $1,800 sofa, bought jointly, kept by one of you after two years, means a payment of $540. Nobody loves that number. Both of you can live with it, which is the whole point. Small stuff, plates and lamps and the air fryer, isn't worth tracking. Set the threshold at $250 and let everything below it go to whoever's holding it.

This is the section where an actual document beats three text threads and a shared note nobody has opened since March. Tools like Servanda walk both of you through the same set of questions and produce one written agreement you've each seen and accepted, which matters more than the format: the value is that neither of you can later remember it differently.

One more thing that belongs here, because it's the largest sum of money in the article. If you're moving into a home one of you owns, paying "rent" to your partner gives you no stake in that property, and cohabiting couples in England and Wales have no automatic financial claim on each other. There is no such thing as common law marriage, however long you live together, a point Resolution and Citizens Advice both make repeatedly while cohabiting families remain the fastest-growing family type in the UK according to ONS Families and Households data. If you contribute to a deposit, a mortgage, or a $20,000 kitchen renovation, record whether it's a gift, a loan, or a claim on the property, and get separate legal advice on that one item. A note in a shared document is not enough for property.

Mistake 4: Your money agreement covers the rent and ignores the $7 items you'll actually fight about

Rent gets discussed because it arrives as a bill with a number on it. The arguments that repeat every month are about toilet paper, bin bags, the takeaway someone said they'd get, and the streaming subscriptions sitting on one person's card. Those need rules more than the rent does, because there's no invoice to settle them.

What this looks like in practice: one of you notices the kitchen roll is finished and buys it. Every time. There's no ledger and no complaint, just a running total in one person's head. Then some unrelated Tuesday it arrives as "I'm not asking you for four dollars, I'm asking why I'm always the one who notices." That fight is not about four dollars, and it also is, which is why the money agreement should catch it.

Rules that hold up:

• One shared card or one weekly reconcile. A card attached to the joint account for groceries and household goods is the low-friction option. If you'd rather split, pick a day: Sunday evening, using a split-expenses app, everything logged before you go to bed. Weekly, not monthly. Monthly means arguing about receipts from three weeks ago.
• Any new recurring cost over $25 a month gets agreed before signup. Gym, streaming, meal boxes, the storage unit. This single line prevents more friction than any other rule on the list.
• Write down what happens when someone forgets. Not a penalty. A default: if the shared card wasn't on you, you pay and log it, and it comes out of the joint account on Sunday. The point is to remove the moment where forgetting becomes a character judgement.
• Name the labour, in money terms. If one of you does the shopping, the cooking, and most of the cleaning, either that's balanced somewhere else or you're paying $120 a month for a cleaner out of joint money. Both are fine answers. Deciding in advance is what stops it being a fight in month nine.
• Guests. Pick a threshold: stays over five nights, the host covers the extra groceries. Sounds petty on paper. Saves an argument about someone's brother and three weeks of oat milk.

Mistake 5: Treating it as one conversation instead of a document with a review date

A financial agreement before moving in together has a shelf life of about a year, so put the review in both calendars the same day you sign it. Forty-five minutes, twice a year, with one of those sessions landing sixty days before your lease renewal date so you can still act on what you decide.

The failure mode is quiet. You set a proportional split at 38.5% and 61.5%, and then one of you gets a $9,000 raise, the other goes freelance and their income swings between $2,100 and $4,800 a month, and the rent goes up 6% at renewal. Nobody recalculates. The percentages that were carefully fair in March are quietly unfair by November, and it surfaces as a fight about who was supposed to descale the coffee machine. Every couple who says "we don't really argue about money" and then argues constantly about small domestic things is often living in a version of this.

Make the review boring and short. Four questions, in this order:

1. What are our shared monthly costs now, actually, from the last three statements?
2. What is each person's net monthly income now, and what does the percentage split come to on those numbers?
3. What went on the shared purchases list since last time, and is anything missing?
4. Is anything in here quietly annoying one of us?

That last question is the one that earns the forty-five minutes. Ask it directly and wait, because the answer is usually a small specific thing, and small specific things are fixable in a sentence of writing.

Also list the events that trigger an early review instead of waiting for the calendar: either income changing by more than 10%, a job loss, new debt over $5,000, a car, a pet, a house move, one of you being off work for more than a month. Any of those makes the current numbers wrong immediately.

And keep versions. Date the document, keep the old one, note what changed and when. Not for a court. For the two of you in eighteen months, when one of you says "we never agreed that" and the other can open a file that says you did, on the 14th of April, and here is what you both signed. Put the first review date in your phones now, while the lease is still unsigned and you both still want to be generous with each other.