Married couples could receive up to £150 a year in tax breaks under plans revealed by the Conservatives on Saturday.
If elected the party say they will offer a partially transferable personal allowance to married couples and same-sex civil partners earning up to £44,000.
The proposals have been slammed by the other main political parties, with the Liberal Democrats describing them as “patronising drivel” and Labour labelling them “unfair”.
The tax break is expected to benefit around four million of the 12.3 million married couples in Britain. It is set to cost around £550 million.
David Cameron said the marriage tax break plans, along with moves to end the couple penalty in the benefits system, add up to a “very pro-commitment, very pro-family, very pro-tackling poverty policy”.
Mr Cameron said he thought in the course of an entire Parliament, the Tories could “go further” with the plans.
Lord Carey, the former Archbishop of Canterbury, welcomed the plans, and the Mothers’ Union said the money could make a great difference to couples with a low income.
But Labour derided the idea, with Yvette Cooper, the Work and Pensions Secretary, saying the plans won’t help children, and that the proposals are “unfair, irresponsible, out of touch and out of date”.
Lib Dem leader Nick Clegg also criticised the plans, commenting: “Miriam and I got married for love, not for three quid a week. It’s patronising drivel.”
But the Tories insisted the plans were more about the message of supporting commitment than the money involved.
Under the Tory proposals, someone not working would be able to transfer up to £750 of their tax-free allowance to their married partner.
The plans mean that a spouse who was working would be able to save up to £150 in tax.
For example, someone earning £30,000 a year currently receives a tax-free allowance of £6,475. They therefore pay tax on £23,525 of their income.
Under the proposals, their non-working spouse would be able to transfer part of their tax-free allowance. Therefore, the working partner would only pay tax on £22,775 of their income, a tax saving of £150.
Lord Carey of Clifton, the former Archbishop of Canterbury, said: “The recognition of marriage in the tax system is a long overdue restatement of the centrality of this institution to the common good of our society.
“Ironically, it was the Conservative Party which weakened the married persons’ tax allowance, it’s entirely appropriate that this party should now atone for that failure.”
And Reg Bailey, chief executive of the Mothers’ Union, said: “We believe that marriage should be supported within the tax system.
“While the income boost may seem small to many, to couples or families living on a low income the fiscal boost could be significant.”
Mike Judge from The Christian Institute said of marriage: “It is the most stable relationship for adults, and the best environment for raising children.
“Of course people don’t get married for the tax benefits, they get married because they love each other. But every marriage needs a bit of support, and recognition in the tax system would be a welcome step.”
And Christian group CARE will say in a policy paper next week: “Although most marriages are the result of romance, they must be sustained over many years ‘in sickness and in health’ and thus down to earth, practical support for this key institution is very important.”