Under the Conservatives' plans, one member of a married couple or civil partnership will be allowed to transfer £1,000 of their tax-free personal allowance to their partner.
The party said the scheme will be worth up to £200 a year for four million couples, including civil partnerships.
Couples will receive the benefit at the end of the tax year in 2016.
Married couples will receive a £1,000 transferable tax break from April 2015, the Prime Minister has revealed.
"The values of marriage are give and take, support and sacrifice – values that we need more of," David Cameron said, writing in the Daily Mail.