Plans for marriage tax breaks to be published 'shortly'
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 some time in the autumn.
Mr Cameron has been under pressure from Tory backbenchers to honour a plan for tax breaks made in the 2010 manifesto.
Labour opposes 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.
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.
Mr Cameron said: "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."
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.
'Help all families'
The prime minister said he had not seen Mr Loughton's proposed change to the Finance Bill, but added: "I don't think that the amendment is in line with the plans that we have.
"The government is going to do this itself, very shortly, so I think we should let the government get on with it, itself."
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".
But Deputy Prime Minister Nick Clegg has called the proposals "patronising drivel that belong in the Edwardian age".
For Labour, shadow treasury minister Catherine McKinnell said: "At a time when the Government's failed economic policies mean living standards are falling, we should be helping all families and not just some.
"Millions of people who are separated, widowed or divorced, as well as married couples where both partners work and use all their personal allowance, won't get any help from this out of touch policy."