How to split ownership fairly when deposits aren't equal

Co-buyers in England and Wales almost always want to own as tenants in common. This lets each owner hold a defined percentage share, which can be unequal, and lets each person leave their share to whoever they choose in a will. Joint tenants own the whole property together in equal, undivided shares, and if one owner dies their share passes automatically to the others. That is fine for married couples and rarely right for friends or siblings.

Your conveyancer records the tenancy type on the Land Registry form, and it is far easier to set correctly at purchase than to change afterwards.

Deposit-proportional: shares mirror deposit contributions. If you put in £40,000 and your co-buyer £12,000 on a £52,000 total deposit, the split is roughly 77/23 of the deposit pot, with the mortgage portion usually split by who services it.

Equal shares with a recorded loan: you both own 50/50, but the larger depositor's extra contribution is recorded as a first charge to be repaid off the top on sale. This keeps day-to-day life simple and still protects the person who put in more.

Blended: shares are calculated from deposit plus each person's share of mortgage capital repaid over time. This is the fairest arithmetic and the most work, so it needs a spreadsheet and an annual review clause.

Ownership shares and monthly contributions are separate questions. A co-buyer with a 25% share may still pay 50% of bills because they use the property equally. Write down which costs are split by share (mortgage capital, major works, insurance) and which are split by use (utilities, council tax, broadband).

Also agree what happens to home improvements. A new kitchen paid for by one owner should either be repaid on sale or recognised as an adjustment to shares, not quietly absorbed.

Whatever you agree is only enforceable if it is written into a Declaration (or Deed) of Trust, signed by all owners and prepared alongside the purchase. It should state each person's percentage, the exact deposit figures, how any loan between owners is repaid, and how shares are recalculated if contributions change.

Expect to pay a few hundred pounds for this document. Against a property worth hundreds of thousands, it is the cheapest insurance in the whole transaction.