Co-Buying Property Agreement: 2026 UK Guide

By The Chipkie Team, Personal Finance Editorial Team  ·  Last updated 18 August 2026

Buying with a partner, a sibling or two friends is now one of the few realistic routes onto the ladder in much of Britain — and a co-buying property agreement is the document that decides whether that arrangement ends well or ends in court. The mortgage gets you the keys. The paperwork between the buyers decides who owns what, who pays what, and what happens when one of you wants out.

Most co-buyers get the conveyancing done properly and the ownership terms not at all. That gap is where the money is lost.

Key Takeaways

• On a joint mortgage, liability is joint and several: the lender can pursue any one borrower for 100% of the debt, not just their notional share.
• Without a Declaration of Trust, the law and HMRC will generally treat co-owners as holding equal beneficial shares, no matter who paid what deposit.
• Under TOLATA 1996, any co-owner can apply to court to force a sale of the property, even if the others refuse.
• Obligations given in a deed carry a 12-year limitation period under the Limitation Act 1980, compared with 6 years for an ordinary contract — one reason to execute your agreement as a deed.
• If part of the deposit comes from family, lenders require a gifted deposit letter confirming the giver retains no interest in the property. If the money is really a loan, it must be disclosed.

What is a co-buying property agreement and what does it actually do?

It is a private, binding contract between the people buying a property together. It records ownership shares, who pays which bills, how one owner exits, and how disputes are resolved. It sits alongside — not inside — the mortgage and the title. Conveyancers rarely draft one unless you ask.

A complete agreement for co-buyers usually covers:

• Beneficial shares: the percentage each person owns, and how it was calculated.
• Contributions: deposit, mortgage payments, Stamp Duty, legal fees, and how future overpayments affect shares.
• Occupancy: who lives there, whether a lodger is allowed, and what rent an absent owner receives.
• Renovation consent: a spend threshold above which all owners must agree in writing.
• Exit terms: notice period, valuation method, right of first refusal, buy-out mechanism.
• Death and default: what happens if someone dies, loses their job, or stops paying.
• Dispute resolution: mediation before litigation.

Practically, you need two documents: a Declaration of Trust (which fixes the beneficial interests and is the document a court and HMRC will look at) and a broader co-ownership agreement dealing with day-to-day conduct. Register the property as tenants in common, not joint tenants — tenancy in common allows unequal shares and lets each owner leave their share by will rather than it passing automatically to the survivors. Ask your solicitor to enter a Form A restriction at the Land Registry.

How do you handle unequal deposit contributions between buyers?

Unequal deposit contributions must be documented in a Declaration of Trust, stating whether the extra money is additional equity or a repayable loan. If you say nothing, co-owners are generally presumed to hold equal beneficial shares — so a buyer who put in £60,000 against a partner’s £10,000 can find themselves splitting the sale proceeds 50/50.

There are three defensible models when buying with friends and working out ownership shares:

Our experience across the agreements our users create is that the “deposit returned first” model causes the fewest arguments, because it survives a falling market as well as a rising one. Spell out what happens to negative equity too — most agreements are silent on losses.

Will lenders accept a deposit that came from family or another co-buyer?

Only if the source is disclosed correctly. UK lenders will accept a genuine gift from a close relative, supported by a gifted deposit letter confirming the money is a gift and the giver retains no interest in the property and no right of repayment. A deposit that is really a loan is a different animal and many lenders will refuse it outright.

This is where co-buyers get into serious trouble. If your parents “gift” you £40,000, sign the lender’s gift letter, and your Declaration of Trust then records that £40,000 as repayable to them on sale, the letter is false. That is mortgage fraud, not a technicality — and it is prosecutable. The same applies if one co-buyer signs a gift declaration for money they expect back from the other.

What makes a lender declaration false:

• The “gift” is repayable, in whole or in part, on sale or on any other trigger.
• The giver is to receive a share of the equity, a charge, or any beneficial interest.
• The money came from someone other than the person who signed.
• The funds are borrowed (credit card, personal loan, overdraft) and this was not disclosed.

If the family money is genuinely a loan, say so and let the lender assess it — some will consider it, factoring the repayments into affordability. If it is genuinely a gift, the giver must accept they cannot get it back. There is no middle option, and structuring it as a secret loan is refused wherever it is discovered. See our guide to setting up a Bank of Mum and Dad loan agreement without the family drama.

On the family side, HMRC allows an annual gift exemption of £3,000 per tax year, with one unused prior year available to carry forward, and small gifts of £250 per recipient. Larger gifts are potentially exempt transfers under the seven-year rule: survive seven years and the gift falls out of the estate. Taper relief between three and seven years reduces the tax due, not the value of the gift — a distinction almost every family gets wrong. The inheritance tax nil-rate band is £325,000 and frozen, per HMRC.

What legal risks do co-buyers most often miss?

The big four are joint and several liability, forced sale under TOLATA 1996, reduced future borrowing capacity, and the Stamp Duty higher rate where any co-buyer already owns property. Each can cost tens of thousands and none of them is obvious from the mortgage paperwork.

1. Joint and several liability. If your co-owner stops paying, the lender comes to you for the full monthly payment — and your credit file suffers for their arrears.
2. Forced sale. Under the Trusts of Land and Appointment of Trustees Act 1996, any co-owner can apply to court for an order for sale. A well-drafted co-ownership exit clause makes this far less likely by giving a contractual route out first.
3. Future capacity. Lenders stress-test each applicant against the entire mortgage debt, not their share. Wanting to buy alone later may prove impossible until you are removed from the title.
4. Stamp Duty. If either buyer already owns property anywhere in the world, the higher rates for additional dwellings apply to the whole purchase price — and first-time buyer relief is lost for both. Check the current rate on GOV.UK before you offer.
5. Capital Gains Tax. Private residence relief only covers periods when the property was your main home; an owner who moves out may face a CGT bill on their share.

Also review life cover, income protection, and buildings insurance together — free guidance is available from MoneyHelper, and any adviser you use should be on the FCA register. Our wider guide to buying a house with friends in 2026 goes further on insurance and occupancy terms.

What should a co-ownership exit clause contain?

A notice period (typically three to six months), an agreed valuation method (two or three independent valuations, averaged), a right of first refusal for remaining owners, a payment deadline for the buy-out, and a fallback requiring open-market sale if no owner can buy. Without these, the only exit is litigation.

Do we need a Declaration of Trust if we are married?

Usually not for ownership purposes, since married couples and civil partners are treated as a single unit for many tax and matrimonial rules and the courts have wide discretion on divorce. But it remains useful where one spouse contributed inherited money, or where a parent’s contribution needs recording as a loan.

Can we change our ownership shares later?

Yes. You can execute a deed of variation to the Declaration of Trust, for example after one owner funds an extension. Notify your lender and take tax advice first, because transferring a beneficial share can trigger Stamp Duty where mortgage debt is assumed, and may have Capital Gains Tax consequences.

Should the agreement be a deed?

Yes, wherever practical. Under the Limitation Act 1980, obligations in a deed can be enforced for 12 years, against 6 years for a standard contract. A deed also removes arguments about whether “consideration” was given — important where one party’s obligation is simply to repay money later.

What should you do next?

Sort the paperwork before you exchange, not after. Agree shares in writing, decide honestly whether family money is a gift or a loan, and instruct your conveyancer on tenancy in common and a Declaration of Trust. If technology can speed this up, our overview of co-buying property technology is a good starting point.

If part of the purchase involves money moving between family or friends, put it on paper properly: create a clear, written loan agreement with Chipkie in minutes so everyone knows exactly what is owed, when, and to whom.

Co-owning a home works well for thousands of people every year. It works because they wrote down what they agreed while they still agreed on it — not because they trusted each other more than you do.

Disclaimer: The information provided in this article is for informational purposes only and should not be considered financial or legal advice. Property and lending laws in the United Kingdom vary and may change over time. We always recommend consulting with a qualified solicitor and mortgage broker before entering into a property purchase or financial arrangement with another party.