David Cameron has signalled he is planning further action to reward marriage through the tax system, on the eve of the expected introduction of an allowance for some married couples.
Chancellor George Osborne is expected to use Thursday's Autumn Statement to announce details of a transferable tax allowance worth £200 a year to an estimated four million couples from 2015, at a cost of £700 million.
But the Prime Minister - who made recognising marriage in the tax system a central plank of his general election manifesto in 2010 - told reporters that he regards it only as "the start of something" and he wants to go further when he is able to.
Speaking during his visit to China, Mr Cameron said: "We will be making this change to back marriage in the tax system. It's a change I strongly support. It's very similar to what we set out in our manifesto.
"It's something I have long wanted to do so I am pleased we will be achieving it.
"I believe in marriage, I believe marriage should be recognised in the tax system. I see this as, yes, a start of something I would like to extend further."
The proposal has come under fire from critics because it will not be available to the poorest households, which have no allowances to transfer, and appears to favour the traditional family with a working father and a stay-at-home mother.
Julianne Marriott, of the Don't Judge My Family campaign, said: "The Government is already planning to spend £700 million promoting a fantasy 1950s family with marriage tax breaks that will only go to one third of married couples and just one in five families with children, despite there being absolutely no evidence they will encourage people to marry or stay married.
"The idea that even more money will be spent on what the Prime Minister himself has called a 'signal' is outrageous. The Government should be spending any spare cash it has on helping, not judging families. This could include investing in childcare for all, reversing £430 million Sure Start cuts and plans to reduce payments to newly widowed parents and providing free relationship counselling for all couples that need help."
Mr Cameron also restated his support for Mr Osborne's plan to run the state budget on a surplus even after the deficit has been eliminated, which he is aiming to do by 2018.
The plan would effectively mean extending austerity measures until the end of the decade at least, and would make it more difficult for a future Conservative government to cut taxes.
Mr Cameron stressed that he was a "low-tax Tory" but said that more needed to be done to get Britain's finances back in shape.
"The job of reducing the deficit and getting Britain back in the black is in no way done," said Mr Cameron.
"We've cut the deficit by a third but it's still much too big, it still needs to come down further.
"As the Chancellor said in his party conference speech, we want to get to a position where Britain is back in the black, we want to fix the roof when the sun is shining.
"We think that when you have - as we hope to have - some years of economic growth, you should be putting money aside for a rainy day.
"At the same time, I'm a low-tax Tory, I believe in allowing people to keep more of their own money to spend as they choose; that's a very important part of my political views, always has been and always will be.
"But I'm also a fiscal conservative, I believe the first duty of government is to safeguard our economy, and the economy isn't safeguarded properly until you deal with your deficit and make sure that you're in a position where future problems that could come down the road, you're able to absorb them."
Mr Cameron added: "I think the way the Chancellor put it in his conference speech was very good: he said the last crisis took us to the edge, we want to make sure that if there's another one it doesn't push us over the edge. I think that's a very important thing to bear in mind."
Asked if he would like to do more to reduce the burden of tax on middle-income households, Mr Cameron said the Government had already helped this group by legislating to raise the personal threshold below which no income tax is paid to £10,000.
"Lifting the income tax threshold benefits all but the richest because it does benefit people on middle and even higher levels of pay," said the PM.
"By next April it will be worth around £705 to the typical taxpayer so I think it's been a very good way of trying to help families with their finances at a difficult time but recognising that there should be a benefit as we keep the costs of Government down and pay down the deficit."