The evolving meaning of ‘matrimonialisation’ in divorce proceedings

Oxford grad Tatiana Quintavalle explores the recent judgment in Standish v Standish

The Supreme Court’s decision in Standish v Standish was one of the most anticipated and talked about family law judgments of 2025 because of the focus it placed on the idea of ‘matrimonialisation’.

In divorce proceedings, deciding how to divide assets is one of the most important issues to resolve. In order to do this fairly, the courts distinguish between matrimonial and non-matrimonial assets. However, ‘matrimonialisation’ is the process by which non-matrimonial property or asset effectively ‘becomes’ matrimonial because of the way the parties have treated it.

The Supreme Court’s judgment established two central principles in relation to matrimonial finance:

• That non-matrimonial property is not subject to the sharing principle, and

• That property only counts as ‘matrimonialised’ when it has been treated as shared by both parties over a period of time.

In clarifying these boundaries, the Court also touched on an important question: should the presumption of equal division apply to matrimonialised property? In this respect, Standish reveals that questions about matrimonialisation are not yet completely resolved.

The background of the case

Mr and Mrs Standish were a high-net-worth couple, most of whose wealth was from Mr Standish’s pre-marital business ventures. During the marriage, Mr Standish transferred roughly £80 million into his wife’s sole name for tax planning purposes and to benefit their two children. However, in actuality the necessary trusts were never established, so the tax benefits never materialised, leaving open the question of who the money truly belonged to.

At first instance, the High Court found that the £80 million had been matrimonialised and should therefore be divided between the wife and husband, 40% to 60%, in recognition of the funds’ extra-marital source. Both parties appealed to the Court of Appeal: the wife argued that the fact that the money was in her name meant it was hers, and the husband argued that the fact he had made the money before the marriage meant it was his. The Court of Appeal agreed with the husband. Mrs Standish appealed to the Supreme Court, arguing that despite its extra-marital source, Mr Standish’s treatment of the money during the marriage, namely transferring it to her, meant that it had been matrimonialised and should therefore be subject to the sharing principle.

The Supreme Court judgment

The Supreme Court dismissed the appeal, confirming that:

• Non-matrimonial property is not subject to the sharing principle, and

• Property is only matrimonialised when it has been treated as shared by both parties over a period of time.

The first principle is consistent with existing law. The sharing principle is the idea that assets built up during the marriage should normally be split equally, unless there’s a good reason not to. Accordingly, even before this clarification by the Supreme Court, it would have been difficult to imagine a scenario where assets which were entirely separate from the marriage were subject to the sharing principle, rather than being used to meet needs or compensate for relationship-generated disadvantage. Standish therefore clarifies rather than limits the reach of the sharing principle.

The second principle clarifies what counts as matrimonialisation. Although the Supreme Court defined it as property that has been treated as shared over time, the fact that it is difficult to come up with a clear definition as to what should count as treating something as shared highlights the inherently blurry nature of a concept like ‘matrimonialisation’. The Supreme Court additionally clarified that neither dealings with an asset for tax reasons nor for the benefit of children would be sufficient to amount to treating an asset as shared, meaning that Mr Standish’s transfer of his money was not sufficient evidence that he was treating it as shared.

Implications — the presumption of equality?

By clarifying the boundaries of matrimonialisation and its formal decision that non-matrimonial property should not be subject to the sharing principle, Standish prevents sharing claims being made to property with an extra-marital source when a merely tangential connection has been established. However, the Supreme Court’s additional implication that equality should be the presumed starting point for matrimonialised property risks making legitimate claims to partially shared property appear more insignificant or unreasonable than they really are.

The Supreme Court asserted that “once non-matrimonial property is excluded, much of the justification for not applying equality in sharing fades away.” In other words, if property has really been shared, why shouldn’t it be divided equally? At first such reasoning appears logical, however, such a presumption risks oversimplifying a complicated concept. Naturally, assets whose source is matrimonial, should by definition be shared equally, but the same logic doesn’t apply to matrimonialised assets, where the asset has a non-marital source. In these cases, an asset might have become genuinely, but only partially, integrated into a couple’s finances, or have been treated as shared in some ways but not others. In such an instance, one might say the asset belonged to both parties, but more to one than the other. Such ambiguity indicates that an automatic assumption of equality for matrimonialised assets could fail to capture the real nature of the assets, and might discourage courts from classifying anything but the most clearly shared assets as matrimonialised.

Conclusion

The two central principles established by the Supreme Court in Standish provide much needed clarification on the complex topic of matrimonialised property in financial remedies proceedings. However, the implication that the presumption of equality applies when sharing matrimonialised property may oversimplify the peculiar status of these assets.

Tatiana Quintavalle is an Oxford Classics graduate who completed her law conversion at the City Law School last year. She is about to start a paralegal role at Camilla Baldwin Solicitors, and hopes to become a family law barrister.