Unjust enrichment – a limited safety net for non-owning cohabitants

It is increasingly common for friends, family members and unmarried couples to live together in property owned by only one of them. When those arrangements come to an end, a familiar issue arises: one party may have made financial or practical contributions to a home in which they have no legal interest.

This article considers whether the doctrine of unjust enrichment offers meaningful protection to non‑owning cohabitants.

The legal starting point

As a starting point, property ownership is determined by the legal title. Therefore, where legal title to a property is held in one party’s sole name, the other has no automatic entitlement to it.

This can produce outcomes that may feel unfair. For instance, a non‑owning party may have:

• contributed to the deposit or mortgage
• paid for works or improvements to the property
• provided their labour for renovation works
• met other household expenses, thereby freeing up the owner’s resources.

Yet such contributions do not necessarily give rise to legal rights when the relationship breaks down.

What is unjust enrichment?

Unjust enrichment is a restitutionary principle which prevents a party retaining a benefit obtained at another’s expense in circumstances where it would be unjust to do so.

To succeed, a claimant must establish that:

1. The defendant has been enriched.
2. The enrichment was at the claimant’s expense.
3. The enrichment is unjust.
4. There is no applicable defence to the unjust enrichment claim.

The remedy is typically monetary, rather than a proprietary interest in the property.

At first glance, unjust enrichment might appear well suited to cohabitation disputes. However, in practice it is less frequently relied upon. Disputes are more commonly advanced by proprietary claims, particularly constructive trusts and/or proprietary estoppel. Even so, unjust enrichment can serve as a useful fallback where those claims cannot be made out – yet it is often overlooked entirely.

Illustrative cases

The courts have, on occasion, allowed unjust enrichment claims to succeed where proprietary claims have failed.

In Yeoman’s Row Management Ltd & Anor v Cobbe [2008] UKHL 55, the claimant spent considerable time and money securing planning permission further to an oral agreement that they would later purchase the land for £12m. When planning permission was granted, the landowner then sought to increase the purchase price to £20m. Although the claimant’s proprietary claims failed, the court allowed a claim in unjust enrichment.

More recently, in Mate v Mate [2023] EWHC 238 (Ch), a claimant who had undertaken substantial work to unlock development value in family land failed in proprietary estoppel but succeeded in unjust enrichment.

Where unjust enrichment claims fall short in practice

In practice, the main difficulty lies in establishing that the enrichment is legally “unjust”.

The law recognises a limited number of “unjust factors”, including:

• failure of basis (for example, where money is transferred for a purpose that later fails)
• mistake
• duress
• undue influence.

In domestic settings, claimants often rely on failure of basis. However, this can be difficult to establish where contributions are made informally and without clear agreement as to what, if anything, is expected in return. If contributions are voluntary and not made with an expectation of recompense, a claim will fail.

This was illustrated in Walsh v Singh [2009] EWHC 3219, with the judge noting: “If dashed expectations of a long-term domestic relationship open the door to unjust enrichment claims, a wide range of claims which the concept of unjust enrichment was never meant, and is ill equipped, to deal with will come marching through”.

Therein lies the difficulty. The end of a relationship does not, in itself, render past contributions unjust, and the courts are reluctant to recast personal arrangements as financial transactions.

The preferred framework – trusts and estoppel

Given these challenges, property ownership and cohabitation disputes are more commonly resolved through proprietary doctrines:

• Common intention constructive trusts – centred on shared intention and detrimental reliance.
• Proprietary estoppel – based on assurances and reliance.

These doctrines can give rise to rights in the property itself, often making them more attractive than a purely monetary remedy.

Unjust enrichment therefore occupies a secondary role. It is most likely to assist where a claimant cannot establish a trust or estoppel but can still demonstrate enrichment in circumstances recognised as unjust.

Policy considerations

Judicial caution in this area reflects wider policy concerns. The courts are wary of:

• intruding into private relationships
• encouraging litigation arising from domestic breakdown
• undermining the informal nature of such arrangements.

At the same time, there is recognition that strict adherence to legal title can produce harsh outcomes, particularly where one party is financially disadvantaged.

Balancing these considerations remains challenging.

The Birketts view

Unjust enrichment offers a potential, but limited, route to recovery for non‑owning cohabitants.

In most cases, claims are better advanced through constructive trust or proprietary estoppel. However, unjust enrichment retains a residual role and may support a monetary claim where clear, measurable contributions have conferred a distinct benefit on the legal owner and were not intended to be gratuitous.

For now, its application remains confined to more nuanced cases, rather than operating as a primary route to redress.

The Birketts home ownership disputes team specialises in resolving property disputes between former cohabitees. For more information about the topics covered in this article, please contact Laura Tanguay or another member of the home ownership disputes team.