The government is “running out of time” to reform cohabitation laws, family law professionals have warned, following the publication of the latest Office for National Statistics (ONS) estimates of families and household types in the UK.
The newly released figures show a steady growth in cohabitation and an increase in lone parents living with adult children in the UK. In 2025, there were 29 million households in the UK, 66.8% of which contained one family (a couple with or without children or a lone parent living with at least one child). Around 8.6 million people (29.5% of all households) lived alone, a similar proportion to 10 years ago; however, nearly half of those living alone (49.6%) were aged 65 years and over, an increase from 46.9% in 2015.
Although married families continue to make up the largest proportion of all households, due to changing family types there has been a small decrease from 2015 to 2025. Married couples (with and without children) made up two thirds of families in 2015 (66.6%). By comparison, in 2025 65.3% of all households were married families because of small rises in other family types, including lone parent, cohabiting couple, and civil partner couple families.
The ONS estimates there are 3.5 million cohabiting-couple families in 2025 (17.6% of all families); an increase of 17% (from 3.2 million) in 2015.
Despite a promised consultation in the spring of 2026, the government has left “a generation of cohabitees without adequate rights” and is “running out of time” to solve the issue, said James Riby, partner at Charles Russell Speechlys. “[The] Law Commission first made detailed reform proposals nearly 20 years ago, in July 2007,” he added.
“These latest numbers therefore suggest that not only have we left a generation of cohabitees without adequate rights, but the government is fast running out of time to secure the position of the ever growing number of cohabiting families, and those newly formed families still don’t know what if any new system will apply to them.
“It is also interesting to contrast these figures with the stated aspirations of Gen Z adults our firm surveyed last year as part of an independent study into wealth and relationship aspirations of GenZ adults (aged 18-27). Perhaps surprisingly, the survey showed that 75% of GenZ adults aspired to marriage, so perhaps we will see an upturn in the curve again in the years ahead.
“Such a shift may be further bolstered by the government’s forthcoming consultation. Early indications of the focus of reforms are that it will aim to bring consistency and fairness across marriage, civil partnerships and cohabitation, addressing the long-standing weaknesses in the rights of cohabitants and, on the other hand, perhaps also bringing more autonomy and certainty to the outcome on divorce.”
According to Nick Gova, head of family at London law firm Spector Constant & Williams, the cohabitation myth still exists and leaves many families “operating without the legal safety net they often assume they have”.
The rise in lone parents also creates legal complications, he added. “The increase in lone parents living with adult children reflects economic pressure, but legally it creates a far more complex household picture when relationships break down or estates are divided.
“The continued rise in lone father households challenges outdated assumptions around caregiving and reinforces the need for child focused outcomes rather than gender led expectations.
“What the ONS data really shows is that modern families are more fluid, multi generational and legally exposed, while the law still largely assumes much tidier outcomes.”
Cohabitation reform has been described as “a matter of utmost importance” by Alex Davies-Jones, the parliamentary under-secretary of state for justice in response to a parliamentary question earlier this year. The consultation would “consider how best to strengthen the rights of cohabitating couples and the circumstances in which protections may apply, while firmly upholding marriage as one of our most important institutions,” she added.
The consultation is due to be launched in the spring of 2026.
