Buying a house together before marriage – often with unequal deposits, and frequently with help from parents – is increasingly common. Protecting those contributions matters, and the key thing many couples miss is that the right protection changes once you marry. Before the wedding, a declaration of trust records who put in what; once you marry, the family home is usually treated as a shared asset, and a prenup is what carries your intentions through. This guide explains the two documents, why you often need both, and how they protect an unequal deposit fairly.
Before marriage: a declaration of trust
While you are an unmarried couple, the usual tool is a declaration of trust (sometimes with a cohabitation agreement) recording how much each of you put in and how the property would be split if you sold or separated. This matters because unmarried couples do not have the same financial claims on each other as married ones – there is no "common-law marriage" in England & Wales – so the paperwork does most of the work. See prenup vs declaration of trust for how they differ.
What changes when you marry
Marriage changes the picture significantly. The family home in particular tends to be treated as a shared, matrimonial asset, tied up with both partners' housing needs. A declaration of trust made beforehand may carry less weight once you are married, because the court's duty to reach a fair outcome under the Matrimonial Causes Act 1973 takes over. That is exactly where a prenup comes in.
How a prenup protects your deposit
A prenup can carry your intentions through into the marriage – recording that each partner's original deposit is returned to them, while any growth or joint contributions are shared fairly. A typical structure looks like this:
- each partner's original deposit is repaid to them first;
- any parental gift is returned to the partner whose family provided it (see protecting a family gift);
- the remaining equity and growth is shared in agreed proportions.
Set the figures out in your disclosure so the contributions are clear, and see protecting a property with a prenup for the wider approach.
If only one of you owns, or will own, the home
Where one partner owns the property, or will hold it in their sole name, the position is different again – see prenups when one partner owns the home. Either way, recording contributions in writing before things get complicated is what avoids a dispute later.
The fair approach
Because a home meets a basic need, a court will not let an agreement leave a partner – or any children – without somewhere to live (see are prenups legally binding?). Protecting your deposit while sharing what you build together is the fair, durable approach – and a sensible reason to consider a prenup if you are buying before the wedding.
Buying a house before marriage: protect your deposit
When buying a house before marriage, protect your deposit with the right document at each stage: a declaration of trust while you are unmarried, then a prenup as you marry, because the family home is usually treated as a shared asset once you are wed. The prenup carries your intentions through – returning each partner's original deposit while sharing growth fairly – so unequal contributions are not simply absorbed into the pot.
Why the prenup carries weight: Radmacher
The reason a prenup is the right document once you marry is Radmacher v Granatino (2010), in which the Supreme Court held that a court should give effect to a freely made, fair agreement unless it would be unfair to hold the parties to it. A prenup is not automatically binding – the court keeps its discretion under the Matrimonial Causes Act 1973, and the housing needs of a partner and any children come first – but a fair clause returning each partner’s deposit before sharing the rest, made with disclosure and independent legal advice on both sides, is exactly the kind a court will respect. A declaration of trust made before the wedding does not carry the same weight once you are married, which is why the prenup is what actually protects your deposit as a couple.
A worked example: unequal deposits
Imagine two partners buy a £400,000 home before marrying. One puts in a £100,000 deposit, half of it a gift from their parents; the other puts in £20,000. A declaration of trust records those contributions while they are unmarried. When they marry a year later, the home becomes the family home, and without a prenup the court’s duty to reach a fair overall outcome can override the trust – potentially treating the equity as simply shared. A prenup can carry the intention through: each deposit is returned first (with the parental gift going back to the right side of the family), and the remaining equity and growth are shared in agreed proportions. That protects the larger contribution without leaving the other partner – or any children – without a home.
The two documents, and why you often need both
It helps to see the declaration of trust and the prenup as a relay, each carrying the baton for its stage of the relationship:
- A declaration of trust (often with a cohabitation agreement) protects you while unmarried, when there is no such thing as “common-law marriage” and the paperwork does the work.
- A prenup protects you as you marry, carrying your intentions into a world where the family home is treated as a shared asset.
See prenup vs declaration of trust for how the two differ, and protecting a property with a prenup for the wider approach where one partner brings a home in.
Common mistakes when buying before the wedding
- Relying on a verbal understanding about whose money was whose – memories fade and disputes grow; put it in writing.
- Assuming a declaration of trust is enough once married – it may carry less weight, so add a prenup.
- Not recording a parental gift properly – document it so it returns to the right family (see protecting a family gift).
- Leaving it to the last minute – sign the prenup well before the wedding to avoid any suggestion of pressure (see when to sign a prenup).
Joint tenants or tenants in common: how you hold the title
How you own the property legally is a decision most couples make almost in passing at the conveyancing stage, yet it has a real bearing on protecting an unequal deposit. In England & Wales co-owners hold either as joint tenants – where you own the whole together and, on death, the survivor automatically takes it – or as tenants in common, where you each own a defined share that you can set unequally and leave by will. If one of you is putting in far more, holding as tenants in common in shares that reflect your contributions, recorded in a declaration of trust, is usually the sensible route while you are unmarried. A joint tenancy, by contrast, points towards equal ownership regardless of who paid what. None of this overrides what happens once you marry – the family home is still treated as a shared asset and the court’s duty to reach a fair outcome takes over – which is precisely why the prenup is needed to carry your intentions through. But getting the title and the trust right at the outset makes the whole picture consistent and easier to evidence.
What if you never marry
It is worth remembering that the plan may change, and the documents behave very differently if the wedding does not happen. There is no such thing as “common-law marriage” in England & Wales, so an unmarried couple who split have no automatic claims on each other’s property – the declaration of trust (ideally with a cohabitation agreement) does the heavy lifting, and it continues to govern the position for as long as you remain unmarried. The prenup only takes effect on marriage. This is a good reason to put the declaration of trust in place when you buy, rather than waiting for the prenup: it protects you immediately, whatever happens next, and the prenup then layers on top when you marry. Leaving both to the last minute is the classic mistake – sign the prenup well before the wedding (the Law Commission suggested at least 28 days) to avoid any suggestion of pressure (see when to sign a prenup).
Buying a house before marriage: FAQs
Does the prenup carry weight after Radmacher?
Yes – since Radmacher v Granatino (2010) a fair clause returning each deposit is given real weight, though needs come first (see are prenups legally binding?).
When should we sign the prenup?
Well before the wedding – the Law Commission suggested at least 28 days – to avoid any suggestion of pressure (see when to sign a prenup).
How do we protect unequal deposits?
Record each deposit so it is returned first, then share the remaining equity in agreed proportions (see how to make a prenup fair).
Does a declaration of trust survive marriage?
It may carry less weight once you marry, which is why a prenup matters too (see prenup vs declaration of trust).
What if only one of us owns the home?
See prenups when one partner owns the home.
Do I need both a declaration of trust and a prenup?
Often yes – the trust protects you while unmarried, the prenup carries it through the marriage.
How do I protect a parental deposit?
Record it clearly, so it returns to the right side of the family (see protecting a family gift).
Is a cohabitation agreement the same as a prenup?
No – a cohabitation agreement is for unmarried couples (see prenup vs cohabitation agreement).
Create your prenuptial agreement online
UK Prenup lets couples in England & Wales create a clear, fair prenuptial agreement online from £199, with your document generated instantly as a PDF. See how it works or get started.
UK Prenup is not a law firm and does not provide legal advice. A prenuptial agreement in England & Wales is not automatically binding, and both partners should take independent legal advice before signing.