Joint Ownership Agreement UK: Cars, Boats, Aircraft

What this document is

A joint ownership agreement is a private contract between two or more people who together own a physical asset, most commonly a vehicle, boat or light aircraft. It sits alongside the legal title to the asset (the V5C for a car, for example) and records the commercial arrangement the owners have agreed between themselves.

The document usually names each owner, sets out their percentage share, and explains how costs, use and decisions will be handled day to day. It will also deal with the less pleasant scenarios: one owner wanting to sell up, a dispute about usage, damage or write-off, death or bankruptcy of a co-owner, and how disagreements get resolved.

For cars, the agreement does not override DVLA records, only one person can be the registered keeper, so the agreement needs to make clear that being the keeper is an administrative role, not a statement of who actually owns the vehicle. For boats and aircraft, registration rules differ again and the agreement needs to reflect that reality. Done properly, it is a short, practical document that prevents most of the arguments people have after the fact.

How to use this document

1. Agree the basics before drafting anything. Sit down with your co-owners and talk through ownership shares, how much each of you is contributing, who uses the asset and when, and how ongoing costs like insurance, fuel, mooring, hangarage and servicing will be split. Getting this aligned in conversation first saves hours of redrafting later and surfaces any mismatched expectations early.
2. Record who is the registered keeper or holder. For a car, only one name goes on the V5C with DVLA, and that person is responsible for tax, SORN and receiving penalty notices. For a boat on the Small Ships Register or an aircraft on the G-register with the CAA, similar rules apply. Your agreement should name the keeper and make clear this is administrative, not a transfer of ownership.
3. Set out usage, costs and decision-making. Spell out how bookings or usage slots work, how routine costs are paid (a joint account often helps), what happens with unexpected repairs, and what spending threshold requires unanimous agreement. For aircraft and boats, also cover who organises annual inspections, insurance renewals and any required certifications.
4. Deal with exit, death and disputes. The most important part of the agreement covers what happens when someone wants out. Include a right of first refusal for the other owners, a valuation method, a sensible notice period, and what happens on death or bankruptcy. Add a simple dispute clause pointing to mediation before court, which usually keeps costs sane.
5. Sign, date and store copies. Each owner should sign the agreement, ideally with a witness, and keep their own copy. Store a copy with the vehicle or vessel paperwork and consider lodging one with a trusted third party. Review the agreement if circumstances change, for instance if a new co-owner joins or the asset is significantly upgraded.

Common questions