Former Tory Chancellor Nigel Lawson says marriage tax breaks should be more generous and introduced sooner.
He thinks it should be worth more than the £200 a year which is currently proposed by the Government.
The Government wants the policy introduced in April 2015 – just a month before the General Election.
But Lord Lawson says it should happen sooner, otherwise it would be easy for a Labour government to roll back.
He said: “I think it should be up and running during the lifetime of this Parliament.
“It makes it easier to reverse it if it’s not up and running because you’re not taking anything away from people that they already have.”
He also said embedding the tax break sooner than just before the General Election “gives us the opportunity to ask for it to be increased subsequently”.
The former Chancellor, who served in the role under Margaret Thatcher, also commented that the proposed tax break amount was “understandable”, but that he would support it being increased.
The allowance would apply to married couples who are both basic rate tax payers, and where one spouse earns less than the personal tax allowance.
In a speech he was also expected to criticise the Liberal Democrats for “foot-dragging” on the issue.
Downing Street said the marriage tax plans, which will also include same-sex couples, show the Government “values commitment”.
Earlier this month the Marriage Foundation described the planned break as a step in the right direction, but could go further.
Harry Benson, from the group, said: “The real disgrace is that we have turned our backs on marriage for far too long. It has cost us dear.”
In February this year Nick Clegg said the tax break was unfair on people who choose not to marry.
He said: “You don’t need the taxman to tell you whether you should get married or not.”
However in July a woman who grew up in a fatherless family on an inner city council estate strongly criticised the Deputy Prime Minister’s comments.
Journalist Selina Gray said in the Daily Mail that the Deputy Prime Minister would change his mind if he visited her local neighbourhood for the day.
She said he would “witness the devastating effect on people of a society that does not value marriage”.