George Osborne has revealed a tax break for married couples will be included in the upcoming Autumn Statement, in a move that is likely to please many backbench Tory MPs.
Speaking to journalists in Westminster on Thursday afternoon, the chancellor insisted he was "absolutely committed" to the policy.
"I've always committed to introducing a married couples tax break, David Cameron campaign to be the leader of the party on that promise. I was his campaign manager," he said.
And he unexpectedly announced that tax break for people who are married will be included in the financial statement due later this year - likely to be in November or December. Osborne said: "I think we can expect to see it in the Autumn Statement."
Conservative MP Tim Loughton, who has long campaigned on the issue, welcomed the chancellor's revelation.
"It is great news to have this commitment to a firm timeline on married couples transferable tax allowances from the chancellor himself," he said.
"All the studies show that marriage works in the best interests of most children yet figures today show how this has been a declining institution.
"In initiating this modest first step at last to recognising marriage in the tax system the Government is sending out a very strong signal that marriage and the commitment it demonstrates is good for families, children and society, both socially and financially and we should not be afraid to stand up for it."
The move is likely to cause friction within the coalition, as despite it being included in the coalition agreement it is opposed by Nick Clegg and the Lib Dems.
The deputy prime minister recently savaged the plan, which would give back around £150 a year to couples who are married, as "unfair".
"I have never understood the virtue of a policy that basically says to people who are not married: you will pay more tax than people who are married or, more particularly, married according to the particular definition of marriage held by the Conservative Party," Clegg said in early July.
"If you have got hundreds of millions of pounds to spend on tax breaks like that then I would much rather spend it on all working families to improve the tax breaks we are going to give them on childcare, for instance.
"Instead, for reasons that I have never quite understood, the Conservatives want to basically say to a widow...you are not going to benefit from a tax break even though you were married and you lost your husband.
He added: "A woman who has been abandoned by her husband suddenly doesn't get the tax break even though she believes in marriage."
Under the terms of the coalition agreement Lib Dem MPs are allowed to abstain in any vote on a tax break for married couples.