A Roommate Agreement is a private contract between co-tenants who share a rental property, establishing domestic rules, financial obligations, and dispute resolution procedures that supplement but do not replace the master lease with the landlord. Unlike a sublease where one party holds the primary lease, a roommate agreement typically governs relationships among co-tenants who are all named on the same lease or among individuals sharing a dwelling where one is the primary leaseholder.

The legal enforceability of roommate agreements depends on state contract law principles. Because roommate agreements satisfy the essential elements of a contract — offer, acceptance, consideration, and mutual assent — they are generally enforceable in court as private agreements. However, any provision that conflicts with the master lease or state landlord-tenant law is unenforceable. For example, a roommate agreement cannot override the landlord's rights under the primary lease or waive protections guaranteed by statute.

Joint and several liability is a critical concept in roommate arrangements. When multiple tenants sign a lease, most leases impose joint and several liability, meaning the landlord can pursue any individual tenant for the full amount of unpaid rent or damages under the Restatement (Second) of Contracts. The roommate agreement creates a separate right of contribution among the co-tenants, allowing a roommate who pays more than their agreed share to seek reimbursement from the others.

College students and young professionals moving into a shared apartment need a roommate agreement before the first month's rent is due. Disputes over utility payments, cleaning responsibilities, and guest policies are the leading causes of roommate conflicts, and a written agreement establishes expectations before habits form and resentments develop.

Existing roommate arrangements that have been operating informally need a written agreement when a new roommate joins or when a recurring dispute reveals the absence of clear rules. Adding a new roommate mid-lease often requires landlord approval and an amendment to the master lease, and the roommate agreement should be executed simultaneously with the lease modification.

Co-tenants with significantly different financial contributions — such as when one roommate occupies the master bedroom and another takes a smaller room — need an agreement that documents the negotiated rent split. Without written terms, a departing roommate may dispute the allocation and seek reimbursement for alleged overpayments.

Roommates who bring personal property of significant value, such as electronics, furniture, or artwork, into shared spaces benefit from an agreement that documents ownership and establishes liability for damage. The agreement prevents disputes about who owns shared household items purchased during the cohabitation and defines the process for dividing or replacing jointly purchased property when the arrangement ends.

The financial allocation section must specify each roommate's share of rent, how the total rent payment is collected and submitted to the landlord, and the deadline for each roommate's contribution. If one roommate collects all payments and submits a single check, the agreement should designate this responsibility and establish consequences for late individual contributions.

Utility cost-sharing provisions should detail which utilities are shared (electricity, gas, water, internet, streaming services), the division formula (equal split, usage-based, or proportional to room size), and who holds each account. The agreement should specify the payment deadline relative to the billing cycle and the procedure if one roommate consistently underpays or overpays.

Common area usage rules must address cleaning schedules and standards, kitchen storage allocation, refrigerator shelf assignments, bathroom schedules in single-bathroom units, and shared living space etiquette. These provisions should be specific enough to resolve disputes without being so rigid that they become impractical.

Guest and overnight visitor policies should define notice requirements, frequency limits, and duration caps for overnight guests. Extended guest stays can create unauthorized occupancy issues under the master lease and may violate local occupancy codes. The agreement should specify when a guest becomes a de facto roommate requiring a formal addition to the arrangement.

Termination and departure procedures must specify the notice period one roommate must provide before vacating, responsibility for finding a replacement, the departing roommate's obligations for their share of remaining lease obligations, and the process for returning security deposit shares. The agreement should address the practical question of whether the remaining roommates have approval rights over replacement candidates, subject to Fair Housing Act restrictions on discriminatory selection criteria.