Prime Minister David Cameron is set to accelerate plans for a married tax allowance by putting legislation before parliament in November.
The proposals to give married couples an extra tax break was included in the Conservative party manifesto and coalition agreement.
Labour has pledged to vote against any plans while Liberal Democrats are allowed to abstain under the terms of the coalition agreement.
Cameron has been forced to act to head off moves by Tory backbenchers to introduce similar proposals by amending the finance bill.
The BBC reports the proposals would allow spouses who do not work and pay no income tax to transfer part of their annual tax-free allowance to their husband or wife if their partner earns less than the higher rate tax band.
Higher rate tax currently kicks in at £41,451 and the Tories estimate it would make four million married couples and civil partners £150.
Cameron says: “The point is that we are going to be putting in place the marriage tax proposal in law.
“We will be announcing plans for that in this Parliament, quite shortly in fact.”