The new law will come into force from 1 July, giving gay couples the right to marry.
Homosexuality was decriminalised in Australia in 1994 and is now recognised by the law.
The same-sex marriage bill was defeated in the Victorian Senate last year, and is expected to pass in the Lower House of Parliament this week.
What are the main points of the new law?
Same-sex couples will be able to marry in the states of Victoria and Queensland.
The new law does not change the laws on civil unions, civil partnerships, adoption, surrogacy, surrogates or guardianships.
Marriage will only be allowed between two people of the same sex, or if both people have been diagnosed as having the same medical condition.
Same sex couples will only receive equal protection under the law, including protections under the Equality Act.
Same sexual couples will not be able get married unless their partner has received medical treatment for a mental health condition.
How will the new laws affect gay couples?
1)Same-gender couples will still be allowed to wed in some states.
The Victorian Supreme Court has ruled same-gender marriage to be illegal.
2)Same sex marriage will not come into effect in New South Wales and Queensland, and will only apply in those states where it is already legal.
3)Marriage licenses will only have to be issued by a magistrate or registrar, or a registered nurse, as opposed to a physician or psychiatrist.
4)Same or different marriage is illegal in some Australian states, including Tasmania, Western Australia, South Australia, Victoria and South Queensland.
What about other religious groups?
The new legislation does not affect religious groups that believe marriage is between one man and one woman.
They will be allowed in the same states as gay couples.
Why is the law being changed?
A key part of the law is that same- sex couples are now recognised as the legal parents of a child.
The legal age of consent for marriage in Australia is 18, but gay and lesbian couples can marry before they reach that age.
The legislation has also changed the definition of “marriage”.
Will same- gender couples get married?
Same-sex relationships are not legal in Australia, so same-sexual couples cannot get married.
They must get married at a ceremony and only the couple who is the parent of the child can get married as a married couple.
Will gay and lesbians be able marry?
No, same- and gay-sex marriages are not legally recognised in Australia.
However, a same- or opposite-sex couple can apply to marry as a couple.
If the couple applies to get married, their application is considered by a judge.
Who is eligible for the new legislation?
Same- and opposite-gender relationships are legal in the following states and territories: Victoria, Western Australian, South Australian, Northern Territory, Tasmania, Queensland, South West Australia, Northern Rivers and the Australian Capital Territory.
Are same- sexual relationships recognised by Australia’s Family Law Act?
Yes, same sex relationships are recognised by all state and territory laws and all of the Family Law Acts.
Can I get married to my partner if I am not married?
Yes, same or opposite sex couples can get marriage licenses.
Marriage licenses can only be issued to a couple who has been diagnosed with a mental illness.
Where can I get more information?
The law will be released on 1 July.
For more information, visit the Equality Commission website.