The Government is considering a range of options which would provide for greater fairness between married and cohabiting couples in areas such as tax, inheritance and social welfare.
The recommendations of a working group on domestic partnership, which were discussed at Cabinet this week, also suggest gay marriage or a civil partnership scheme as a way of providing greater recognition for same-sex couples, The Irish Times has learned.
The options are set out in a 97-page "options paper" report commissioned by the Minister for Justice, Michael McDowell.
The Cabinet is due to consider the findings again at next week's meeting. However, any potential legislative change is unlikely before the general election.
Any changes would have a significant impact for tens of thousands of cohabiting and same-sex couples if acted on by the Government. Latest census figures for 2002 show there are about 77,000 cohabiting couples and 1,300 same-sex couples in the State, although new figures due to be published next year are expected to show this number has increased substantially.
For cohabiting couples, the report suggests a number of options including a presumptive rights scheme which would automatically provide legal recognition for cohabitees after a period of time, such as three years.
The rights would allow for greater fairness for cohabiting couples in areas such as tax, property and inheritance.
For same-sex couples, the report suggests gay marriage as an option, although it cautions that there may be constitutional difficulties with this.
Mr McDowell and Taoiseach Bertie Ahern had previously ruled out such a move and warned that such steps would be fraught with legal and constitutional problems. The Attorney General has advised the Government that such a move would require a referendum.
The option report also suggests a civil partnership scheme for gay couples, such as the scheme in the UK, which would extend marriage-like privileges to gay couples but stop short of marriage.
These partnerships grant next-of-kin rights to gay people and allow them to benefit from a dead partner's pension, while remaining exempt from inheritance tax on their partner's home. Partners are also able to dissolve the agreement in a form of divorce.
Another area examined in the report is options for partnerships for people who are not in a sexual relationship but have a dependent or shared relationship, such as two siblings living together.
However, the report points to a lack of research into this area and said more work needs to be done before setting out options in this regard. It is understood that the Departments of Finance and Social and Family Affairs also had concerns that such a measure could be open to fraud on a large scale.
The 11-person working group on domestic partnership was chaired by solicitor and chairwoman of the Legal Aid Board Anne Colley. It also included representatives from Government departments and a range of non-governmental organisations.
While the report sets out a range of options for the Government and draws heavily from international practice, it does not recommend a specific form of action.
Mr McDowell has previously said that the conclusions are likely to form a "sound" basis for legislative change in the area. Mr Ahern has also signalled his support for fairer treatment of same-sex couples.
The Law Reform Commission, in a consultation paper on cohabitation in 2004, also suggested that cohabiting couples should be entitled to significant tax breaks on property that they inherit from their partners. It is due to publish a major report on the issue at the end of next week. However, providing greater recognition to same-sex and cohabiting couples could have significant cost implications.