New proposals from the Law Commission would see gay and lesbian couples who have not formed a civil partnership gain some financial rights similar to those of married couples.
The Commission, who advise parliament on reform to the law, said that many couples of both orientations are missing out because the law at the moment is complicated and unclear.
They propose that any couple who share a child or have been living together for more than two years would be entitled to make a claim over assets on separation.
There would be no principle that assets be divided equally or any ongoing maintenance payments.
Contribution to the relationship would determine if assets should be shared.
Similar measures are already in place in Scotland.
There are over two million cohabiting couples in England and Wales, and an estimated 1.25 million children are being raised in these households.
Stuart Bridge of the Law Commission, said:
“More and more families involve couples who are living together but who are not married.
“The law that currently applies to resolve property disputes between such couples on separation is unclear and complicated, and it can produce unfair outcomes.
“This causes serious hardship not only to the cohabitants themselves, but also to their children.”
The proposal is in stark contrast to the recent policy announcement from Tory leader David Cameron.
He advocated changing the tax system to reward marriage and civil partnerships by introducing a married couples tax allowance, worth around £20 a week, aimed at making it easier for one parent to stay at home.
The tax rebate would apply to married couples and civil partners regardless of whether or not the couples have children.
The Law Commission said they were not trying to “undermine” marriage but to protect people of all orientations who were contributing to a relationship that then broke up, or to provide clearer financial remedies for children.
Advocates for marriage said the measures were unnecessary.
Jill Kirby of the Centre for Policy Studies told the BBC:
“If a man and a woman want to create a family together, then the most durable contract available to them is marriage.
“If they decide not to marry, then I think consequences must flow from that, and that if we introduce… a kind of substitute version, as the Law Commission proposes, then it does detract from that institution and I think will lead to more confusion.”
The family lawyers’ organisation Resolution spokesman David Allison told The Independent:
“We fully support the Law Commission’s proposals … and will be pressing the government to introduce new legislation without delay.”
To read the Commission’s report into cohabitation click here.