Conservative MPs say that married couples are currently disadvantaged in the tax system
David Cameron has said the government will bring forward proposals for a transferable tax allowance for married couples and civil partners "shortly".
The BBC understands it will happen sometime in the autumn.
Mr Cameron has been under pressure to honour a pledge to introduce tax breaks made in his 2010 election manifesto.
But Labour oppose the idea and the Lib Dems were given a specific opt-out in the coalition agreement which means they do not have to support it.
Under plans being considered, wives and husbands who do not work and pay no income tax would be able to transfer part of their annual tax-free allowance to their spouse if their partner earns less than the higher rate of tax, which currently kicks in for people earning £41,451 or more.
In 2010, the Tories said it would make four million married couples and civil partners £150 a year better off.
'Close vote'No detail is yet clear about the amount of transferable allowance proposed now, but it would only apply to basic rate taxpayers and may not be in force before the next election.
It is understood that the proposals could be unveiled to Parliament at the time of the Autumn Statement, around the end of November.
BBC political correspondent Gary O'Donoghue said putting a timescale on the proposal should help the government head off an attempt made this week by one of its own backbenchers, former minister Tim Loughton, to amend the finance bill in favour of such an allowance.
But with Labour against the idea, and the Lib Dems allowed to abstain on it, any vote in the future would be very close, he added.
The Tory manifesto said recognising marriage and civil partnerships in the tax system would "send an important signal that we value couples and the commitment that people make when they get married".
Source: BBC News - Business http://www.bbc.co.uk/news/uk-politics-23120462#sa-ns_mchannel=rss&ns_source=PublicRSS20-sa
