Shadow chancellor George Osborne has insisted the Tories were ready for government, with tax breaks for married couples a key plank of their strategy for a stronger society.
Tory leader David Cameron has been a long-standing supporter of using the tax system to support marriage, but it was thought Mr Osborne was less keen on the idea.
However the shadow chancellor said there was "no disagreement" between the two men on the issue - although he conceded they did differ on other area of policy.
In an interview with the Daily Telegraph he said: "Marriage will be recognised in the tax system.
"If I am David's Chancellor, which I fully expect to be, then I will implement that.
"There is no disagreement there at all. Of course, everyone is entitled to choose how to live their lives and some marriages do fail, but we know that, in general, marriage is an institution that contributes to building a stronger society.
"That is why Labour was wrong to stop supporting it through the tax system."
Details of the policy, likely to appeal to Conservative traditionalists, have not been finalised, nor has it been revealed how the tax cut will be funded.
Giving an insight into the workings at the top of the party as it prepares the policies which it hopes will win the next election, Mr Osborne said he and Mr Cameron "don't always agree on everything".
He added: "But on the big fundamentals - the changes necessary to the Conservative Party, keeping the Conservative Party on the centre ground in British politics and the economic changes that we need to make - we pretty much see eye to eye."
