1. How it usually happens
Cohabitation or flatshare agreements often start informally. Two partners decide to live together, friends rent a place, someone temporarily hosts an acquaintance, a flatmate takes over a room, or a relative moves in "for a few weeks" and then weeks start stretching like camping elastic bands.
At first everything seems simple. Rent is split, utilities shared, someone brings the sofa, someone the washing machine, someone an air fryer promising to change lives. Then come practical questions: who pays what, whose name is on the contract, who paid the deposit, what happens if someone leaves early, who buys furniture, who keeps the pet, who answers for damage, how to manage long-term guests, parties, cleaning, common areas, and personal items.
The difficulty arises because home is an emotional space before an economic one. A plate left in the sink can become a symbol of a value system. An unpaid bill can feel like betrayal. The sofa bought "together" can turn into a museum-worthy enigma: together in what shares, with whose money, and who takes it when someone leaves?
There are also less obvious perspectives. Someone entering an already inhabited home may feel like a permanent guest, even if contributing to expenses. The contract holder may feel responsible for everything. Someone who bought lots of furniture might fear losing it or not being reimbursed. Someone paying small daily expenses can end up contributing more than others without noticing, like the silent character who always buys toilet paper and detergent, one day discovering they financed half the building.
Documenting agreements does not strip spontaneity from shared life. It means giving clear shape to practical decisions, so people can live together with fewer suspicions and more clean towels.
2. What you need to prove
For cohabitation or flatsharing, the point to prove is the content of agreements between people: who lives in the property, since when, with what financial contribution, what responsibilities, which goods are personal or shared, and what happens when a person leaves the house.
It is also necessary to document initial state of places and present objects. If a door was already ruined, a wall had stains, an appliance was already faulty, or a piece of furniture belonged only to one person, it is better to be able to show it with clear files.
It can be useful to prove:
- version of cohabitation or flatsharing agreements;
- entry date of each person;
- amount for rent, common expenses, utilities, and deposit;
- who paid what and by what method;
- breakdown of bills and recurring expenses;
- ownership or availability of furniture, appliances, and personal items;
- initial state of rooms, furnishings, walls, floors, systems, and accessories;
- any defects already present in the house;
- agreements on guests, pets, use of common spaces, and cleaning rotas;
- agreements on early departure, notice, flatmate replacement, and sum refunds;
- content of chats, emails, or documents confirming agreements;
- any subsequent modifications to initial agreements.
The practical question is: "If in six months someone changes their version, which files explain what we decided?" Domestic memory is creative: it remembers perfectly who burnt the pan in 2022, but often forgets who promised to pay for Internet.
3. What to collect
Useful documentation combines written agreements, payment proofs, images of house state, and communications between people. You don't need a monumental archive; you need what prevents misunderstandings on major decisions.
You can collect:
- a PDF with cohabitation or flatsharing agreements;
- chat or emails where all people confirm agreements;
- receipts for rent, deposit, utilities, building fees, or common costs;
- relevant bank statements or payment confirmations, obscuring unnecessary data;
- photos and video of initial house state;
- photos of private rooms, common spaces, kitchen, bathroom, balcony, cellar, garage, or storage;
- details of already present damage, like cracks, stains, scratches, breakages, or faulty appliances;
- list of furniture, appliances, and items brought by each;
- purchase receipts for shared or personal goods;
- simple inventory of common objects;
- any agreements on pets, guests, cleaning, noise, smoking, smart working, or space use;
- documents received from landlord, management, or utility providers;
- quotes or invoices for repairs, maintenance, or common purchases;
- original photo, video, PDF, screenshot, and document files.
For valuable items, it pays to be specific. "TV in living room" is only useful up to a point; "TV brand X, 55 inches, bought by Sara, with attached receipt, common use during cohabitation" avoids end-of-season arguments, when everyone discovers a sentimental bond with the remote control.
4. How to proceed
The most practical way is preparing a simple document before moving in or as soon as cohabitation starts. It can be one or two pages long, written in normal language. Include names of involved people, address, start date, amounts, payment rules, deposit management, common expenses, personal goods, shared goods, and exit modalities.
Then do a house tour with your phone. Photograph and record main environments with good light: entrance, kitchen, bathroom, bedrooms, living room, balconies, cellar, garage, appliances, and already damaged spots. A slow, orderly video is often more useful than thirty diagonal artistic photos. The house shouldn't look like a design magazine; it must be recognisable.
After collecting everything, send the summary to the other flatmates and ask for written confirmation. Confirmation can happen via email or chat, as long as it is clear. If agreements change, create a new document version and keep the previous one too. Cohabitations evolve: a new flatmate arrives, a bill changes, someone buys a table, someone decides a two-metre tall plant is a "common expense" because it improves room energy.
Practical procedure:
- prepare document with main agreements;
- indicate amounts, deadlines, deposit, utilities, and common expenses;
- clarify what is personal and what is shared;
- photograph initial state of house and furnishings;
- document already present defects;
- keep receipts and payment proofs;
- ask for written confirmation from all involved people;
- create an orderly folder with agreements, photos, payments, and communications;
- timestamp main files, like agreement, inventory, initial photos, and confirmations;
- update documentation when people, expenses, or rules change.
A concrete example: three flatmates move in. One pays deposit, one puts Internet in their name, one brings washing machine and table. The document states who paid what, how others reimburse, who owns which objects, how bills are split, and what notice is needed to leave. It is less epic than handing over keys with pizza on the floor, but much more useful when someone decides to move to Berlin "in two weeks".
5. Mistakes to avoid
The most frequent mistake is leaving agreements in vague phrases. "We split everything" sounds simple, but says nothing about deposit, variable bills, extraordinary expenses, common products, repairs, long-term guests, or furniture bought together. Better write a few clear points than rely on the house's permanent good mood, a notoriously unstable resource when coffee runs out.
Another common error is documenting only payments and forgetting location states. If a wall was already stained or furniture already broken, photograph it immediately. Also avoid confusing personal items and common goods: when cohabitation ends, material things suddenly become very philosophical. "It belonged to everyone" can mean "I bought it but you used it too" or "we paid for it in three".
Beware of personal data. Receipts, contracts, bank screenshots, and documents may contain unnecessary information. Keep originals carefully and share only essential versions when needed. Also avoid aggressive or ironic messages in written agreements: "Marco washes dishes at least once in his life" might be funny today and complicate conversation tomorrow.
Besides cryptographic attestation, consider signed receipts for large sums, traceable payments, periodic checks of common expenses, an updated inventory, and consulting a professional when cohabitation involves significant amounts, ownership, complex economic responsibilities, or delicate family situations.
Free timestamping lets you secure main cohabitation files in time without adding costs to domestic management that already has enough.
6. After documenting
After documenting agreements, use them as a live reference. When a bill arrives, save the receipt and note who paid. When a common good is bought, keep the receipt and write how cost was split. When a person enters or leaves the house, update the document and create a new written confirmation.
If a disagreement arises, restart from collected materials: agreements, payments, initial photos, inventory, messages. Send a calm summary with points to clarify and a concrete proposal. For example: expense balance, deposit return, personal items collection, damage repair, utility update. Domestic arguments improve greatly when they shift from "you always do this" to "these are the three amounts left open".
If the situation remains blocked, you can turn to a legal consultant, mediation service, consumer or tenant protection association, real estate professional, or private dispute management expert. If landlord, building administration, utility providers, or insurances are involved, contact them with orderly communications and relevant documents.
When cohabitation ends, do a final check of house and objects. Photograph state of places, keep confirmations of key return, final payments, refunds, and agreements on furniture or common goods. Closing well prevents a shelf, bill, or ficus plant from becoming the sequel to an already finished cohabitation.
Organised documentation does not make flatmates perfect and does not wash dishes for them, but helps keep facts, expenses, and memories separate. In a shared house, that is already an excellent start.