Home improvements and your share of the house: does paying for them change it?

Home improvements and your share of the house: what is the rule?

When it comes to home improvements and your share of the house, the rule is simple: if one of you paid for home improvements, your share of the house doesn’t change automatically when you’re not married. That’s true for a new kitchen, a loft conversion or a £30,000 extension. This guide covers England and Wales.

Married couples and civil partners have a specific rule for this (more on that below). Unmarried couples don’t. There’s no common-law marriage, however long you’ve lived together, and fewer than half of the people we surveyed (18 of 39) knew that living together doesn’t give you married couples’ rights. So what an improvement does to your shares depends on two things: whose name the home is in, and what you’ve written down.

Your situation	What paying for work does by default
Joint names, shares recorded	Shares stay as written
Joint names, nothing recorded	Half each is the start
One partner’s name only	Owner starts with it all

None of this means the money doesn’t matter. It means the law won’t sort it out for you, so the fairest thing you can do for each other is agree what the money means before the builders arrive.

What if you own the home in joint names?

If you recorded your shares. If you bought as tenants in common and wrote your shares in the transfer form or a declaration of trust, those shares usually decide it. In Pankhania v Chandegra, the Court of Appeal said a written declaration of shares is conclusive unless it’s set aside for something like fraud or mistake. In Stack v Dowden, the House of Lords said an express declaration is conclusive unless it’s varied by a later agreement or affected by proprietary estoppel (a promise-based claim, more on that below). So a big improvement leaves your recorded shares where they are, unless you both agree to change them. If you do, ask a solicitor how to record the change. A declaration of trust over land must be shown in signed writing.

If you recorded nothing. If you own as joint tenants, or nothing says what your shares are, the starting point is equal shares, even if one of you paid more. A court can depart from half each only if there’s evidence you both intended something different. In Stack v Dowden, the House of Lords said many more factors than money paid in can matter, and that cases where joint owners are taken to have intended something other than half each will be very unusual.

In Jones v Kernott, the Supreme Court said what you both intended can be shown to have changed after you bought. Where a court can’t tell what you intended about your shares, it decides what’s fair, looking at the whole course of dealing between you in relation to the home. So a big improvement paid for by one of you can be part of that picture. But a court would need evidence that you both intended the payment to change your shares, and finding out in court is slow, costly and uncertain for you both.

If you borrow the money jointly, for example by adding to a joint mortgage, Citizens Advice says that if you’re both named on the mortgage, you’re both responsible for the payments, and that you may be responsible for the whole of a debt in joint names. Who actually makes the payments can still differ, so agree that too.

What if the home is in one partner’s name?

If the home is in one partner’s name only, the owner starts with all of it. The other partner has no automatic share, whatever they’ve paid for.

That can change. Advicenow lists the contributions that can help show a share, and they include mortgage repayments and funding repairs, renovation and refurbishment. But Advicenow also says proving a share is usually very tricky, and if you can’t agree, the partner who isn’t on the title has to go to the civil court. Citizens Advice says you’d need to show a judge how you contributed towards paying for the home, and that this can be difficult.

The question a court asks is what you both intended. Paying for a new kitchen in a partner’s home might be a gift, a contribution to running the home you both live in, or buying into it. The money alone doesn’t say which.

There’s one more route. If the owner promised the other partner a share in the home, and they reasonably relied on that promise to their cost, for example by paying for an extension, a court can step in. Lawyers call this proprietary estoppel. In Guest v Guest, the Supreme Court said the aim is to prevent, or make up for, the unfairness of someone going back on a promise that another person relied on to their detriment. These claims depend heavily on the facts and need legal advice.

This is fair to say to both of you. The owner’s home stays theirs unless you both intend otherwise, but what you say and do around a big spend can sometimes create a share. The partner paying gets certainty only if it’s written down. Our guide to when your partner owns the house and you’re not on the deeds covers this in more detail.

Why doesn’t the married couples’ rule apply to you?

Section 37 of the Matrimonial Proceedings and Property Act 1970 says that if a husband or wife makes a substantial contribution, in money or money’s worth, to improving property that either or both of them has a share in, they are treated as getting a share or a bigger share, unless they agreed otherwise. The size is whatever they agreed or, if they didn’t agree, whatever a court thinks just. Section 65 of the Civil Partnership Act 2004 gives civil partners the same rule.

Both sections are written for spouses and civil partners only. If you’re living together without being married or in a civil partnership, neither applies to you.

The exception is engaged couples. Under section 2 of the Law Reform (Miscellaneous Provisions) Act 1970, when an engagement to marry ends, the rules on married couples’ property, including section 37, apply to property either of you had an interest in while you were engaged. If you ask a court to settle it using the married couples’ property procedure (section 17 of the Married Women’s Property Act 1882), you must apply within three years of the engagement ending, so if that’s you, get legal advice soon.

What are the fair ways to agree it?

There are three common answers. Each can be fair; the point is that you both choose one, ideally before anyone pays.

Option	What it means
Shared, no change	Work is a shared cost; shares stay
Cost back first	Payer gets what they paid back first
Decide each time	You agree before each big spend

1. Shared, no change. You treat big work as a shared cost, split equally or as you agree at the time, and paying for it doesn’t change your shares. This suits couples who pool money, or who see one partner paying for the kitchen as balanced by the other paying more of the bills.

2. Whoever pays gets the cost back first. If one of you pays more than your half, the extra comes back to them first from what’s left after the mortgage when you sell, and the rest is shared as your main shares say. They get back what they paid, not any rise in the home’s value, so you only need receipts, not an argument about what the work added. You keep a simple record of each big one-off: what it was, the date, who paid and how much, and you both sign each entry.

3. Decide each time. Before each big spend, you agree who pays and whether it changes your shares, and you write it down. If you didn’t write anything down, it doesn’t change your shares. This suits couples who’d rather not commit now to work they haven’t planned.

Whichever you choose, set a threshold, for example any single cost of £5,000 or more, so you’re not logging every tin of paint.

Be fair about what isn’t on the invoice. The partner who didn’t pay for the work may have paid more of the bills that year, covered the mortgage while the other was saving, done the labour themselves, or looked after the children during the build. Those are real contributions too. “Decide each time” lets you take them into account: for example, you might agree that only part of the cost comes back first.

These choices map onto the “big one-offs” section of a couples agreement (also called a cohabitation agreement). To see how they fit with your deposits, try the deposit split calculator.

How does this work with real numbers?

Alex and Jordan aren’t married. They bought a £300,000 home in both names, each putting in a £25,000 deposit, with a £250,000 joint mortgage. A few years later Jordan pays £30,000 from savings for a new kitchen and a small extension. Later still they sell for £380,000, with £220,000 of mortgage left. That leaves £160,000.

Alex and Jordan's £160,000, depending on what they wrote down

What they wrote down	Alex gets	Jordan gets
Nothing: joint names, no shares	£80,000	£80,000
Jordan's £30,000 back first	£65,000	£95,000
Shares in proportion to money in	£50,000	£110,000

How the rows work:

• Nothing written down. The starting point is half each, £80,000 each, even though Jordan paid for the work. Jordan could ask a court to find a different intention, but as we saw above, that’s unusual and uncertain.
• Cost back first. Jordan gets £30,000 back first. That leaves £130,000, split equally: £65,000 each. So Alex gets £65,000 and Jordan £95,000.
• Shares in proportion to money in. Alex put in £25,000 and Jordan £55,000 (£25,000 plus £30,000), £80,000 in all. So Alex owns 25/80 and Jordan 55/80. That’s £50,000 and £110,000. This also gives Jordan a bigger share of the rise in value, and they’d need to record the new shares, for example in a declaration of trust.

Now say the work added less than it cost, and they sell for £340,000. With £220,000 of mortgage left, that leaves £120,000.

If they sell for £340,000 instead

What they wrote down	Alex gets	Jordan gets
Nothing: joint names, no shares	£60,000	£60,000
Jordan's £30,000 back first	£45,000	£75,000
Shares in proportion to money in	£37,500	£82,500

With cost back first, Jordan still gets £30,000 first and the £90,000 left is split £45,000 each. Neither row is the right answer for every couple. If Alex had paid an extra £6,000 of the household bills while Jordan saved for the work, they might agree that only £24,000 comes back first. The difference is that with something written down, they both knew the numbers before the work started.

Illustration only: it ignores selling costs, tax and anything else either of you paid.

What happens if you split up and nothing was agreed?

If you agree who gets what, you can settle it between you, ideally in writing and with advice. If you can’t, either owner can ask a court to decide under the Trusts of Land and Appointment of Trustees Act 1996. Under section 14, a court can declare what share each of you has and make orders about the home, including a sale. Under section 15, it considers things like what you intended when you bought it, why you bought it and the welfare of any child who lives there or might be expected to.

Advicenow describes these cases as expensive, stressful and uncertain, and legal costs can eat into the money you’re arguing about. That’s true for the partner who paid for the work and for the one who didn’t. Our guide to what happens to the house if you split up covers selling, buying out and the mortgage.

The law may change. The government consulted on new rights for cohabiting couples from 5 June to 14 August 2026. At 1 October 2026 it’s analysing the responses, and nothing has changed in law. Under the proposals, a court would begin from the position that each of you keeps what you legally own, so recording your shares would still matter.

What should you do before the work starts?

1. Check what you’ve already recorded. Find your transfer form and any declaration of trust, so you both know your current shares. Our declaration of trust guide explains what they do.
2. Talk about what the money means. Shared cost, cost back first, or decide each time? The free 10-minute conversation takes you through big one-offs and the rest side by side, and your answers stay on your device.
3. Agree a threshold for what counts as a big one-off.
4. Write it down and both sign it. Put your choice in a couples agreement. Read what a couples agreement covers and how your agreement counts.
5. Keep records. Quotes, invoices, bank transfers, and a signed note of each big one-off.
6. Change your declaration of trust if your shares should change. You both have to agree, and a solicitor can record it.
7. Get separate legal advice if the home is in one partner’s name and the other is paying for big work, large sums are involved, either of you feels under pressure, or you’re separating now.

If your deposits were different too, our guide to an unequal deposit when buying a house together shows how the same three approaches work for deposits.