Contrary to popular belief, it isn't the case that being a common-law spouse provides built-in protection for cohabiting couples – but there are voluntary arrangements that can provide equivalent financial rights.
Recent changes to the intestacy laws, which determine who can inherit an estate if someone dies without a will, make it easier to claim more of the property of a spouse or civil partner.
However, despite recommendations from the Law Commission, unmarried, cohabiting couples were not given any more rights to a partner's estate in the event of death.
Resolution, an organisation of lawyers that promotes mediation to solve family problems, is campaigning for increased legal protection for couples who live together.
According to the Office for National Statistics, the number of cohabiting couples in the UK has almost doubled since 1996 from 1.5 million to 2.9 million two years ago – and even more today.
Stephen Kirwan, managing director at the law firm Nowell Mellor and the head of Resolution's work on reforming cohabitation law, says live-in partners have "almost no rights" – although many mistakenly believe that couples become "common-law spouses" after a number of years.
In order to protect their own interests and ensure a partner is provided for if one dies – or if the relationship breaks up – cohabiting couples should assess each area of their finances, property and childcare arrangements to see what provisions they need to put in place.
Couples can use cohabitation agreements or declaration-of-trust arrangements, which are both legally binding, to determine who owns what assets and who is entitled to what.
The contracts differ slightly.
A declaration of trust, sometimes known as a deed of trust, sets out exactly what assets each partner is bringing to the relationship and what happens to the assets should they have to be divided.
This contract can set out who pays certain bills and any "extra value" that one partner may have contributed, such as paying for home improvement.