If it is not written, it will be remembered three ways
People move in with good intentions and different memories. One person heard that utilities would be equal. Another heard they would follow the rooms. A third heard that the deposit would come back to whoever "handled it." Six months later those three memories become a fight that feels like a character conflict and is actually a missing page. Write the page before the keys, while everyone still wants to be reasonable.
The page is not a novel and it is not a substitute for the lease. The lease controls the landlord relationship. Your page controls the promises among you. If the lease says you are all liable for the full rent, your page does not erase that. It says how you will settle among yourselves so the landlord gets paid. If your page and the lease disagree, the landlord will follow the lease, and you should know that before you sign either.
Keep the page to one screen or one sheet. A ten-page house constitution will not be read again. The Bill Split calculator can produce the dollar shares you paste into the page. Paste numbers, not "fair shares." Fair is the argument. $800 is a share.
The lines that prevent most fights
Names of the people and the address. The rent amount and each person's share. The reason for unequal shares if they are unequal, in one sentence, such as "shares follow bedroom square footage measured on March 2." The day rent is due to the person who pays the landlord, which should be before the landlord's due date. The utility rules: equal, by nights, or a stated weight, and which utilities are included. The day utility shares are due after the bill is shared.
The deposit: who paid how much, and how a refund will be divided when it returns. If one person paid the whole deposit, the page should say whether the others will repay them, on what schedule, or whether that person alone receives the refund. Silence here is expensive. A buyout amount, if any, should be a number and a date.
Guests: how long a guest can stay before the household talks, and that guest groceries are the host's cost unless agreed. Moving out: how many days of notice you give each other, how rent will be prorated if you allow proration, and what happens to the empty room's share until someone new arrives. The notice you give each other can be stricter than your friendship and still kinder than a surprise.
A sample paragraph you can edit
"We live at the address on the lease. Rent is $2,400. Alex pays $900, Blair pays $800, Casey pays $700, based on room size. Rent shares are due to Alex on the 28th because Alex pays the landlord on the 1st. Electric, gas, and internet are split equally. Shares are due three days after the bill photo is posted. The security deposit was $2,400, paid $800 by each, and any refund will be split the same way after documented deductions. A roommate who leaves gives 30 days' notice to the others. Rent is prorated by day only if the landlord's bill for that month is prorated. Until a replacement is approved by the landlord and by the remaining roommates, the leaving person's share continues through their notice period. Guest stays over seven nights need a group yes. Signed and dated."
That paragraph is dull. Dull is the goal. Edit the numbers to your apartment. Do not delete the deposit sentence or the empty-room sentence to make it friendlier. Those are the sentences you will need when the friendship is having a bad week. If you cannot agree on them now, you are not ready to share the lease, even if the apartment is perfect.
How to sign it without a ceremony
Each person should have a copy. A message that says "reply yes if this matches what we said" is a reasonable lightweight signature if everyone replies in the same thread. A photo of initials on paper is also fine. What matters is that the yes is attached to the words, not to a vibe in a kitchen. If someone wants a change, change the words and ask for a new yes. Do not collect yeses on a draft and then edit the dollars.
Set a review date three or six months out. A review is not an accusation. It is a chance to fix a utility rule that does not fit. Put the date in the calendar when you sign. Households that "will revisit sometime" revisit on the worst day. The date makes the revisit ordinary.
When a new person moves in, they sign the same page or an updated one before they pay a deposit to you. Handing them the wifi password is not the same as handing them the agreement. If they will not sign, you have learned something while it is still easy to unwind. If you already took their money, unwind carefully and in writing anyway. The page is how you avoid discovering the disagreement after the truck leaves.
What the page cannot do
It cannot make a broke month rich. If someone's share is more than they can pay, the page will not create dollars. It can make the shortfall visible early, which is when a smaller room or a different apartment is still possible. It cannot replace renter's insurance, a legal reading of the lease, or a city's deposit rules. It cannot stop a person from breaking their promise. It can make the promise specific so the rest of you know what was broken and what is owed.
Do not include punishments you will not enforce, such as a $100 fee for a dirty pan. Joke penalties become bitterness or get ignored, and then the real lines look optional too. Keep the page to money, dates, and move-out. Chore systems can live on a different note if you want them. Mixing a chore chart with the rent shares invites someone to withhold rent over dishes. Rent is not leverage for dishes. Dishes are a conversation. Rent is the page.
If a dispute later needs a mediator or a legal process, the page is a record of what you intended. It is not a court order. Write it as if a calm stranger will read it, because future you is that stranger. Avoid sarcasm and nicknames. Use the names on the lease.
Store it with the lease
Put the page in the same folder as the lease, the deposit receipt, and the move-in photos. When a bill argument starts, you read the page before you invent a new rule. If the page is silent, you amend it. You do not pretend it said something. Amendments get a new date and a new yes from everyone who is still affected.
Before you sign a lease together, read the page out loud once. It takes a few minutes. Anyone who laughs at a sentence should say what they think it means. If the meanings differ, fix the sentence. That reading is the cheapest time you will ever spend on this apartment. The expensive time is a move-out with no page, three memories, and a landlord who wants one number. Give your future selves the paragraph. They will use it.