Money
- Rent per person, and the date agreed.
- Which bills are shared and who holds each account.
- The day everyone settles up each month.
- What happens if someone is late: a grace period, then what.
Guests
- How many nights a guest can stay before it's a conversation.
- Whether partners who stay most nights contribute to bills.
- Heads-up rules for parties or more than a few people.
Shared space
- Quiet hours on weeknights.
- Kitchen: dishes done same day, fridge shelves, what is shared.
- Bathroom schedule if mornings clash.
Cleaning
- The chore list and rotation.
- The missed-week rule.
- Who buys supplies and how it's reimbursed.
Leaving
- Notice period before someone moves out.
- How a replacement is chosen. Everyone gets a veto, or majority.
- Deposit: how it's split and what damage comes out of it.
How to use it
Fill it in together on the first weekend, not by text. Read it aloud. Date it, and put it somewhere shared. Reopen it only when someone moves in or out, or when something on it clearly isn't working.
The best house rules are boring. They are the ones you never have to bring up.