In a long-awaited but unsurprising ruling issued on 2 July 2025, the UK Supreme Court has provided clarity on how non-matrimonial property should be treated in high-net-worth divorce cases, firmly holding that the sharing principle does not apply to property acquired prior to marriage or through external gifts or inheritance.

Background

The case involved a wealthy former UBS executive, aged 72, and his 57-year-old wife. The couple began their relationship in 2003 and married in 2005.  Prior to their marriage, the husband amassed significant wealth, largely derived from his pre-marital career. In 2017, in anticipation of becoming UK domiciled for tax purposes, the husband transferred £77 million of these assets to the wife with the intention of avoiding inheritance tax. These assets were to be placed in trusts for the benefit of their two children, but the trusts were never established, and the wife retained the assets.

The couple separated in 2020, and their financial dispute ended up before the High Court, the Court of Appeal, and ultimately the Supreme Court.

The Core Legal Issue

The central question was whether the £77 million transfer, termed the “2017 Assets”, should be treated as matrimonial property (and thus subject to the sharing principle) or remain non-matrimonial.

The Supreme Court unanimously found that the majority of the “2017 Assets” retained their non-matrimonial status and were not subject to the sharing principle. It held that while property can become “matrimonialised” through the parties’ conduct over time, the mere act of transferring the assets during marriage for tax planning purposes does not amount to such matrimonialisation

Lower Court Decisions

At first instance, Moor J held that the assets had become matrimonial property due to the transfer, and awarded the wife £45 million, a 40% share of what he calculated to be the total matrimonial pot. The Court of Appeal overturned this, finding that only 25% of the 2017 Assets were matrimonial in nature. The wife was entitled to £25 million, and the case was remitted for a needs assessment.

Supreme Court Judgment

The Supreme Court upheld the Court of Appeal’s decision and used the case to clarify five major legal points:

1. Clear Distinction Between Asset Types: Only matrimonial property is subject to the sharing principle. Non-matrimonial assets, such as those acquired before marriage or received by gift or inheritance, are excluded.
2. Sharing Principle Defined Narrowly: The Court definitively stated that the sharing principle does not apply to non-matrimonial assets. This removes ambiguity left by prior cases.
3. Equal Sharing is the Default, But Only for Matrimonial Property: When assets are matrimonial, they should typically be split equally unless there’s a compelling reason otherwise.
4. Matrimonialisation Explained: Non-matrimonial property can become matrimonial if it is treated over time by both parties as shared. However, this must be demonstrated through conduct, not merely ownership or transfer.
5. Tax-Motivated Transfers Are Not Sharing: Transfers made solely for tax planning, such as the “2017 Assets”, do not indicate an intent to share the assets. The Supreme Court found no evidence that the husband intended the wife to have beneficial ownership of the assets beyond their role in inheritance tax mitigation.

Wider Implications

By firmly ring-fencing non-matrimonial assets from equal division, the judgment in Standish v Standish strengthens the role of prenuptial and postnuptial agreements and  makes these even more worthwhile. It  also confirms  and clarifies the circumstances in which wealthy individuals may, or may not,  be required to share inherited or pre-marital wealth.

Importantly, it confirms that strategic asset transfers, even during a marriage, will not automatically entitle a spouse to a share, unless there is clear, sustained evidence of shared ownership and intent.

Clare Lenaghan leads our Matrimonial and Family Department at Millar McCall Wylie and has been involved in numerous high net worth pre-nuptial and post nuptial financial settlements, including  cases with assets in different jurisdictions.