Understanding Property Co-Ownership Agreements When Buying

Over the past few years, I’ve watched more and more people turn to family members to help them buy a home. The Bank of Mum and Dad has quietly become one of the country’s biggest mortgage lenders, and multi-generational purchases are now a normal part of the market. But here’s the thing that keeps coming up in conversations I have: property law doesn’t automatically understand your family’s financial arrangement. If you buy a house with a parent, sibling, or adult child without a proper legal framework, you’re essentially trusting that nothing will ever go wrong. And when something does — a relationship sours, someone loses their job, or a parent passes away unexpectedly — the legal system defaults to rules that might not match what anyone intended. That’s where a properly drafted co-ownership agreement becomes essential, not optional.

What I’ve noticed over the years is that most people don’t realise how quickly a well-intentioned family arrangement can turn into a legal mess. The Trusts of Land and Appointment of Trustees Act 1996 — TOLATA for short — is the legislation that governs co-ownership disputes, and it’s not designed to sort out who promised what over a kitchen table conversation. If you’re buying with family, you need to understand the two fundamental ownership structures available, and you need a document that records exactly what everyone agreed. Here’s what you actually need to know.

Joint Tenants vs Tenants in Common — The First Decision You’ll Make

The most important legal choice in any co-ownership is whether to hold the property as joint tenants or tenants in common. It’s not a technical detail you can sort out later — it determines who owns what, what happens when someone dies, and whether you can leave your share to someone else in your will. I’ve seen people assume they can change this after completion, and while severance is possible, it’s a formal process that requires notice and documentation. Better to get it right at the start.

Joint tenants hold the property as an undivided whole. There are no distinct shares, and if one owner dies, their interest passes automatically to the survivors under the right of survivorship. You cannot leave your share to someone else in your will because you don’t own a distinct share in the first place. This arrangement works well for couples who want equal rights and a simple inheritance mechanism, but it’s rarely appropriate for family co-purchases where contributions are unequal. Tenants in common, by contrast, hold the property in defined shares — 60/40, 70/30, or whatever reflects the actual contributions. Each owner can leave their share by will, and the shares are recorded at HM Land Registry. This is almost always the better choice when parents are contributing to a deposit, when siblings are buying together, or when the arrangement is explicitly an investment rather than a family home. My first move would be to discuss this with your conveyancer before you exchange contracts, because the default at HM Land Registry depends entirely on how the transfer deed is drafted.

Why Getting It Wrong Costs More Than You Think

The real cost of a poorly documented co-ownership isn’t just legal fees — it’s the breakdown of a relationship that you probably assumed was solid. I’ve seen families that were close for decades fall apart over a property dispute that could have been avoided with a single document. The numbers back this up: around 60% of family property disputes involve undocumented contributions, according to Property Passport UK. That means someone put money in, but there’s no paper trail saying what it was for. Was it a gift? A loan? An equity stake? Without documentation, the legal presumption in English law is that a contribution from a parent to a child is a gift unless the contrary is clearly documented. If you’re the parent who expected to get that money back, or who expected to own a share of the property, you’re in for a very expensive surprise.

Consider a realistic scenario: a parent puts £80,000 towards a child’s deposit. The child and their partner buy the property in joint names as joint tenants. Five years later, the couple separates. The parent expects to get their £80,000 back from the sale proceeds, but the partner argues it was a gift. Under English law, the partner is likely correct unless there’s a document saying otherwise. The parent would need to go to court under TOLATA to try to establish a resulting trust or proprietary estoppel — and that litigation is expensive, uncertain, and takes months. A Declaration of Trust executed before completion would have avoided the entire dispute. If you’re in this situation, I’d strongly recommend speaking with a property lawyer who can draft the right document for your specific circumstances.

Where People Go Wrong With Co-Ownership Agreements

Over the years, I’ve noticed the same mistakes cropping up again and again. They’re not complicated errors — they’re things people assume don’t apply to them because they trust their family. But trust isn’t a legal document, and the law doesn’t care how close you are. Here are the most common pitfalls I see.

Assuming Joint Tenancy Works for Unequal Contributions

This is the single most common mistake. Two people buy a property together. One puts in 70% of the deposit, the other puts in 30%. They hold the property as joint tenants because the conveyancer didn’t explain the difference, or because they assumed “joint” just means “together.” The problem is that joint tenants don’t have defined shares. If they sell, the default is a 50/50 split unless they can prove otherwise. If one dies, the survivor gets everything — the deceased’s 70% contributor can’t leave their share to their own children from a previous relationship. The fix is simple: hold the property as tenants in common with a Declaration of Trust recording the actual shares. A leasehold vs freehold guide might also be useful reading if you’re buying a flat, as the ownership structure interacts with the lease terms.

Not Documenting Parental Contributions

I’ve already touched on this, but it’s worth repeating because it’s so common. A parent gives money for a deposit. Everyone agrees verbally that it’s a loan or that the parent gets a share. No one writes it down. Years later, when the property is sold or the relationship ends, the parent’s version of events conflicts with the child’s partner’s version. The law presumes it’s a gift. The parent loses their money. The only way to avoid this is to document the arrangement at the time — either as a Declaration of Trust recording an equity stake, a loan agreement with a charge registered at HM Land Registry, or a gift letter confirming no expectation of repayment (which many mortgage lenders require anyway). If you’re unsure which option is right, a real estate lawyer can walk you through the implications of each.

Ignoring What Happens When Someone Wants Out

Most co-ownership agreements don’t address the obvious question: what happens if one person wants to sell and the other doesn’t? Without a clause in the Declaration of Trust, you’re back to TOLATA, which means applying to the County Court for an order to force a sale. That process is slow, expensive, and unpredictable. A well-drafted Declaration of Trust should include a mechanism for one party to buy out the other, a valuation method, and a dispute resolution process — ideally mediation before any court application. I’ve seen properties sit empty for years because one owner wanted to sell and the other couldn’t afford to buy them out, and neither could agree on a price. A simple clause in the trust deed would have resolved it in weeks.

→ Scroll right to see all columns

Forgetting About the Non-Owning Contributor

Sometimes one person contributes to the purchase price but isn’t on the title — perhaps because a lender won’t accept them as a borrower. This is common when a parent helps with the deposit but can’t or won’t go on the mortgage. Without a Declaration of Trust, that person has no legal interest in the property. They might be able to establish a claim through proprietary estoppel or a resulting trust, but that requires litigation under TOLATA, which is expensive and uncertain. The better approach is to execute a Declaration of Trust before completion that records the non-owning contributor’s interest, even if they’re not on the title. A Form A restriction at HM Land Registry can also prevent the property from being sold without their consent.

How to Set Up a Co-Ownership Agreement That Actually Works

Writing about topics like this takes real time and research. If you buy something through an Amazon link on this page, I may earn a small commission — at no extra cost to you. It’s one of the things that makes it possible to keep BritWealth free to read. I only link to products that are genuinely relevant to the article.

If you’re buying a property with family, here’s the practical process I’d follow. It’s not complicated, but it requires you to be honest about what everyone expects — and to get it in writing before you exchange contracts.

Choose Your Ownership Structure First

Before you do anything else, decide whether you’ll hold the property as joint tenants or tenants in common. This isn’t something you can leave to your conveyancer to sort out at the last minute. If contributions are unequal, if you want to leave your share to someone other than the other owner, or if the arrangement is an investment rather than a family home, tenants in common is almost always the right choice. If you’re a couple buying your first home together and you want the property to pass automatically on death, joint tenancy might be appropriate. Discuss this with your conveyancer before exchange of contracts, because the transfer deed needs to reflect your choice. If you’re unsure about the mortgage implications, a building societies vs banks guide might help you understand which lender is best for your situation.

Draft a Declaration of Trust

This is the single most important document you’ll create. A Declaration of Trust (also called a Deed of Trust) is a legal document, separate from the transfer deed and the mortgage, that records the proportion of the property held by each owner. It should cover: each owner’s percentage share, the contributions each party has made to the purchase (deposit, mortgage payments, renovation costs), how ongoing costs (mortgage, maintenance, insurance, council tax) are to be shared, what happens if one party wants to sell and the other doesn’t, what happens if one party stops paying their share of the mortgage, what happens on the death of one party, whether one party can buy out the other and on what terms, and how disputes will be resolved (for example, by mediation before any court application). The document is executed as a deed and, for co-owners with different shares, should be noted at HM Land Registry via a Form A restriction on the title register. This prevents one owner from disposing of the property without the other’s consent. A financial advisor can also help you understand the tax implications of different ownership structures.

Document Parental Contributions Clearly

If a parent is contributing to the deposit, you need to decide — and document — whether it’s a gift, a loan, or an equity stake. A gift requires a gift letter confirming there’s no expectation of repayment, which many mortgage lenders require to confirm the deposit isn’t a loan. A loan should be documented with a loan agreement, ideally with a charge registered against the property at HM Land Registry to protect the loan in insolvency or sale. An equity stake should be recorded in the Declaration of Trust, giving the parent a proportionate share of the property. Without one of these documents, the law presumes the contribution is a gift, and the parent has no legal right to repayment or a share. I’d recommend speaking with a estate lawyer if the arrangement involves inheritance planning, as the interaction between property ownership and wills can be complex.

Plan for the Future — Including the Worst Case

A good co-ownership agreement doesn’t just cover the happy path. It should address what happens if one owner wants to sell, if one owner stops paying their share of the mortgage, if one owner dies, or if the relationship between the owners breaks down. Include a valuation method for buyouts, a timeline for sale if agreement can’t be reached, and a dispute resolution process that starts with mediation before any court application. I’ve seen too many families end up in court because they assumed they’d never need to think about these scenarios. The cost of drafting a comprehensive Declaration of Trust is a few hundred pounds. The cost of a TOLATA application to the County Court can run into tens of thousands — and that’s before you factor in the damage to your relationships.

• 1
  Choose your ownership structure

  Decide joint tenants or tenants in common before exchange. Discuss with your conveyancer and ensure the transfer deed reflects your choice.

• 2
  Draft a Declaration of Trust

  Work with a solicitor to create a deed covering shares, costs, sale mechanisms, and dispute resolution. Execute it before completion and register a Form A restriction at HM Land Registry.

• 3
  Document all financial contributions

  For parental contributions, choose gift, loan, or equity stake and document accordingly. Get a gift letter if required by your mortgage lender.

• 4
  Plan for disputes and exits

  Include buyout clauses, valuation methods, and a mediation-first dispute resolution process. Store all documents in a shared location accessible to all co-owners.

Frequently Asked Questions

If you’re buying with family, the single most important thing you can do is document everything before you exchange contracts. The cost of a Declaration of Trust is small compared to the cost of a dispute that ends up in court. And if you’re the one contributing money without being on the title, don’t assume your family will remember the arrangement the same way you do years from now. Get it in writing. If this was useful, you might also want to read The Ultimate UK Home Buying Checklist: Are You Truly Ready?

Sources and Further Reading

UK Home Buying: Is It Worth It in 2024? — A balanced look at whether now is the right time to buy, including market conditions and affordability considerations.

Buying Property with Family: Co-Ownership Guide. Property Passport UK, 2024.

Rights and Responsibilities of Co-Owners of Property. UK Legal Guides, 2024.