A British Social Attitudes survey from 2024 found 46% of cohabiting adults thought they were "common law" married. They are not. Common law marriage was abolished in England and Wales in 1753 (Lord Hardwicke's Marriage Act). It still does not exist. Unmarried couples have no automatic claim to each other's property, pensions, or assets if the relationship ends, and no automatic inheritance rights if one partner dies without a will.
The Government has a public consultation on cohabitation reform open from spring 2026, but any law that emerges will take years to come through Parliament. For now, cohabiting couples are on their own.
If you are buying a house together, the legal scaffolding you need is straightforward and not expensive. Most couples skip it because no one tells them to. Then they break up, and a £4,000 conveyancer becomes a £40,000 family law fee.
How you hold the property: joint tenants or tenants in common
When two or more people buy a property together, the Land Registry asks how the title is held. The two options:
- Joint tenants: you both own 100% together. Neither has a separable share. If one dies, the other inherits automatically (right of survivorship). When sold, proceeds split 50/50 regardless of what either contributed.
- Tenants in common: each owns a defined share. Shares can be unequal. Each share passes via your will, not automatically to the other partner. When sold, proceeds split per the share allocation.
For unmarried couples, especially where one partner contributes more (deposit, mortgage payments, or both), tenants in common is almost always right. You record the actual split, you can leave your share to whomever you want, and you avoid the right-of-survivorship trap.
The default if you say nothing is joint tenants. Make sure your conveyancer files Form SEV with the Land Registry to confirm tenants in common, with shares.
Declaration of trust: the document everyone forgets
Tenants in common with shares is the headline. The detail is in a declaration of trust (sometimes called a deed of trust). This is a separate document, drafted by your solicitor, that sets out:
- Each person's share of the property
- How the deposit was paid
- How mortgage payments will be split
- How any major works costs will be split
- What happens if one partner pays more later
- What happens if you split: who gets first refusal, how is the property valued, who can buy out whom
A declaration of trust is recognised by the courts. Without it, if you split, the courts apply general property law and start from the question "who paid what, and what was the intention?" That is an evidence-driven mess that costs both of you tens of thousands.
Cost is typically £400 to £800 plus VAT. Most conveyancers can draft one as part of the purchase. If yours cannot, find one who can.
Cohabitation agreement: the wider one
A declaration of trust covers the property. A cohabitation agreement covers everything else: bank accounts, pets, debts, household goods, what happens if one of you stops working to look after children, what happens if one partner makes a major career sacrifice for the other.
It is not a prenup (those are for married couples). It is a contract between two adults setting out what they have agreed about their financial life together. UK courts have enforced cohabitation agreements as long as they are properly drafted, freely entered into, and do not try to override existing legal obligations like child maintenance.
Cost: £500 to £1,500 to draft.
If you are not married and you are buying a house together, the cost of getting both documents (declaration of trust plus cohabitation agreement) is roughly £1,000 to £2,500 total. The cost of not having them, in a contested separation, is typically 10 to 20 times that.
Wills: the other big gap
Unmarried partners do not inherit from each other under intestacy rules. If your partner dies without a will, their estate goes to their parents, then siblings, then children, depending on circumstances. You get nothing automatically. You can apply under the Inheritance (Provision for Family and Dependants) Act 1975, but you have to go to court, prove financial dependency, and wait. It is expensive and uncertain.
Both partners need a will, naming each other as a beneficiary. This is true even if you do not own a house yet. After buying, update the will to reference the property and your declaration of trust.
Will costs are £150 to £300 each via a solicitor, less if you use a service like Farewill. Do not use a will-writing service that is not authorised; the £30 high-street will is often defective when tested.
What about civil partnership?
Same-sex and opposite-sex couples can enter a civil partnership in England and Wales. It gives almost all the legal protections of marriage: inheritance, pension rights, property rights on dissolution. The cost is around £400 to £600 in fees, plus whatever you spend on the ceremony.
For couples who do not want to get married for personal reasons but want the legal scaffolding, civil partnership is the cleaner path than building all the documents yourselves.
If one partner is gifting or lending the deposit
This comes up a lot. One partner has £40,000 saved or has parents who are helping. The other has £5,000.
Three options to handle the difference:
- Loan from one partner to the other: documented in the declaration of trust. The deposit-rich partner is owed the difference back when the property is sold, before the equity is split.
- Unequal shares as tenants in common: the deposit-rich partner owns a larger percentage. Mortgage and contributions are split per share, not 50/50.
- Gifted deposit from a parent: parent's gift letter goes on the file. The deposit comes from one partner's side. Usually paired with unequal shares to reflect that contribution.
The declaration of trust is where these arrangements live. Do not rely on a verbal agreement, an email, or a hand-shake. Six months in, no one remembers what was actually agreed; six years in, no one is willing to admit what they remember.
Action this week (if you are about to buy together)
- Tell your conveyancer you want to hold as tenants in common with shares reflecting your contributions.
- Ask them to draft a declaration of trust. Get it before exchange.
- Speak to a family solicitor about a cohabitation agreement. Treat it as a separate appointment, not a conveyancing add-on.
- Both write or update wills naming each other.
- If you are cohabiting and did not do this when you bought, speak to a solicitor now. Retrofit declarations of trust are possible.