Treasury sources have tried to dispel the possibility of a backbench battle for the married couples' tax allowance by pledging to introduce it before 2015.
The move seeks to head off anger before Tory MPs realise it will not appear in tomorrow's spending review, despite featuring in the Tory manifesto and the coalition agreement.
The Telegraph reported Treasury minister David Gauke as saying the tax break, worth up to £150m a year, will be introduced before the next election.
It will probably come into force in April 2015, although ministers may choose to legislate in this parliament and implement later if it keeps Tory MPs from causing trouble.
Rebel Tory MPs had been planning to amend the finance bill currently going through parliament to include the tax break.
The tax allowance also appeared in last week's 'alternative Queen's Speech', a collection of dozens of firmly right-wing bills put forward by a small group of Conservative backbenchers as an attempt to drag the government towards a more classically Tory position.
But it is strongly opposed by Nick Clegg and other Liberal Democrats who view it as a paternalistic moral judgement on people's lifestyle choices.
That opposition should not technically be insurmountable. The coalition agreement explicitly made room for a Lib Dem abstention on the policy.
"We will also ensure that provision is made for Liberal Democrat MPs to abstain on budget resolutions to introduce transferable tax allowances for married couples without prejudice to the coalition agreement," it reads.
The policy would allow wives or husbands who do not work to transfer part of their tax-free allowance to their spouse if their partner earned less than the basic rate of tax.
The move has relatively strong public support. A YouGov poll in January found it had 53% support to 36% against.
Among Labour voters, it was 46% to 44% and even among Lib Dems it stood at 47% to 47%.