Fifty-Fifty Feels Fair Until It Isn't: The Couple's Guide to Splitting a Home Purchase

Two salaries. One deposit. One mortgage. And, if you're like most couples buying together, one unspoken assumption: everything gets halved.

It sounds fair. It feels fair. But a 50/50 split between two people earning different amounts, contributing different deposits, with different plans for the future is where a lot of relationships quietly spring a leak. Before you exchange contracts, it's worth having the honest version of the conversation — because by the time it's a problem, it's also a legal one.

Why the Even Split Rarely Reflects Reality

Say one of you earns £48,000 and the other earns £29,000. Splitting the mortgage 50/50 means the lower earner is spending a much bigger chunk of their take-home on the same roof. That might be fine for a while — but if money gets tight, resentment builds in one direction and guilt in the other.

Or flip it: one of you puts £40,000 into the deposit thanks to an inheritance, the other puts in £8,000. If you split the equity evenly and the relationship ends, that £32,000 gap can vanish unless it's written down somewhere. Banks don't care about fairness. They care about names on the mortgage application. The paperwork is where fairness actually lives.

The Deposit: Match the Money to the Deed

The cleanest rule of thumb: your share of the property should broadly reflect what you've put in, unless you've agreed otherwise.

That means if you're contributing unequally to the deposit, you need a declaration of trust (sometimes called a deed of trust). It's a legally binding document that sets out who owns what share of the property. A solicitor can draw one up for a few hundred pounds, which is a bargain compared to the cost of arguing about it later through a solicitor at £250 an hour.

If you're contributing equally and earning equally, you might not need one. But if either of those things isn't true — and for most couples one of them isn't — get it in writing while you both still like each other. That's the point. These documents are cheap and easy when things are good and nearly impossible when they're not.

The Mortgage: Split It Like the Bills, Not Like the Rent

A common approach is to split the mortgage in proportion to income. If you earn 60% of the household income, you pay 60% of the mortgage. It keeps the pressure even on both of you.

Others prefer 50/50 on the mortgage but compensate elsewhere — the higher earner covers the council tax and the car, say. There's no single right answer, but there is a wrong one: leaving it undefined. "We'll sort it out as we go" is how one person ends up paying for the boiler in year three and quietly keeping score.

Whatever you choose, set up a joint account that both of you pay into by standing order on payday. Mortgage, buildings insurance, council tax — it all leaves that account. No chasing, no mental arithmetic, no surprises.

Don't Forget the Deed Itself

Here's the bit that catches couples out: joint tenants vs tenants in common.

• Joint tenants means you both own the whole property together, and if one of you dies, the other automatically inherits the whole thing — regardless of what your will says.
• Tenants in common means you each own a specific share, which can be 50/50 or anything else, and you can leave your share to whoever you like.

If you're contributing unequally, tenants in common is almost always the right call, paired with that declaration of trust. If you're married or planning to be, joint tenancy plus a will might suit you better. Either way, this is a decision, not a default — and the conveyancer will ask you to pick, usually in a five-minute phone call you won't be prepared for.

Improvements: The Loft Conversion Clause

Two years in, one of you funds a £15,000 kitchen. Whose money is that now?

If it's tenants in common with a trust deed, you can agree in advance that improvement costs buy extra equity shares. Some couples keep a simple spreadsheet; others agree that improvements are a gift to the house. The specific answer matters less than having one before the first B&Q receipt.

The Awkward Conversation, Minus the Awkwardness

Nobody wants to open with "what happens if we split up?" So don't. Frame it as the practical checklist it is:

1. What are we each putting into the deposit?
2. What share of the mortgage can each of us comfortably carry?
3. Joint tenants or tenants in common?
4. Do we need a declaration of trust?
5. Who pays for what — and where does it come out of?

Have it over a takeaway, not in a solicitor's office. The goal isn't to plan for failure; it's to make sure the ladder has rungs you both agree on before you start climbing.

Buying together is one of the biggest financial commitments either of you will ever make. Fifty-fifty is a fine place to start the conversation. It's just a terrible place to end it.