Cohabitation rights: new PM Boris Johnson and partner Carrie Symonds's living arrangement puts cohabitation laws in the spotlight

As new Tory Prime Minister Boris Johnson and girlfriend Carrie Symonds prepare to become the first cohabiting couple in Downing Street — taking the flat above No 11 — the spotlight is falling on the millions of other unmarried couples in the UK who live together but stand to lose everything when their other half dies.

The cohabiting culture is growing, according to a new report. One in eight adults in England and Wales lives as half of an unmarried couple and this proportion has risen every year since 2004, to six million people now.

Half of them co-own property and financial assets including cash and shares but the perception of their rights when a partner passes away is “severely skewed”, according to the study by financial analysts Farewill.

Around 53 per cent have assets worth £100,000, while 15 per cent have up to £500,000.

The survey shows almost a third of us wrongly believe that living in the same house for more than five years or raising children together entitles people to ownership of property and investments when the worst happens.

But in fact, if one cohabiting partner dies without leaving a detailed will, the survivor won’t automatically inherit the estate, and that includes any part of the shared home.

“There’s a huge myth that, when you die, the person who you’re in a long-term relationship with, or own a house with, will automatically inherit your estate. This simply isn’t true. The law only applies automatic protection to married couples or those in a civil partnership,” warns Dan Garrett, chief executive of Farewill.

“Being together for a long time doesn’t count, and means you’re entitled to nothing.”

Without a will, the estate will often go to a parent or parent-in-law and an unmarried partner who stays at home to care for children can’t make any claims in their own right for property, maintenance or pension sharing.

“The law as it stands isn’t set up for the modern family,” Garrett adds.

Gillian Mitchell of Gordon Brown LLP agrees that couples that cohabit do not have the same rights as couples that are married or are civil partners of each other. However, steps can be taken to regulate the terms of cohabitation by entering into a 'cohabitation contract'.

“This can provide clarity during the course of a relationship and in the event that it should break down. The majority of cohabiting couples do not take this step,” she says.

The surviving partner can lay claim to an estate but the process is far more complex and adds stress to the bereavement process without an existing cohabiting agreement.

Sharon Heston, a lawyer at BP Collins, also warns that inheritance tax implications should not be overlooked either. "A spouse who inherits is, in the main, exempt from inheritance tax, whereas a co-habitee does not benefit from the same relief,” she advises.

“With blended families on the increase, it is crucial to get expert advice about the best way to draft a will to ensure protection of assets and loved ones,” Heston adds.