A landmark ruling by the Supreme Court to uphold the rights of an unmarried mother has increased the calls for government action on cohabitee rights.
When her partner died in 2014 Siobhan McLaughlin was denied a lump sum bereavement payment of £2,000 and a weekly widowed parent allowance because the couple were unmarried - despite living together for 23 years and having four children.
The ruling will allow people in similar situations to apply for payments but has prompted calls for cohabitees to benefit from other rights.
Rachael Griffin, tax and financial planning expert at Quilter, said high profile court cases surrounding cohabitees is becoming an increasing occurrence and not a trend that the government should be applauding.
She said: "This most recent case serves as a stark reminder that marriage is heavily engrained in our current benefit and tax systems.
"This is a worrying state of affairs and one that merits serious examination by the government. Judgments like these increase the pressure on the government to carefully look inheritance and tax rights to ensure they reflect modern family units."
Despite an initial win when challenging the decision at the High Court in Belfast in 2015 on the grounds of unlawful discrimination based on marital status, Ms McLaughlin’s case was later overturned - but today’s appeal ruling found that Ms McLaughlin is entitled to access the widowed parent’s allowance despite her marital status.
Earlier this year the Court of Appeal ruled against the government, allowing a woman to claim bereavement damages in relation to her partner of 16 years.
Figures from the Office for National Statistics show the number of cohabiting couple families increased by 30 per cent between 2004 and 2014, making them the fastest growing type of family in the UK.
There are currently six million people cohabiting, making up one in 10 of the population.
There is no such thing as common law marriage in UK law but 51 per cent of respondents to the British Social Attitudes Survey thought unmarried couples who live together for some time probably or definitely had a 'common law marriage' which gives them the same legal rights as married couples, despite this is not being legally the case.
The Cohabitation Rights Bill, which would provide certain protections for people who live together as a couple and make provision for the property of deceased persons who are survived by a cohabitant, was introduced as a private members bill to the House of Lords in 2014 but has not since progressed.