Camilla Parker Bowles wants the title of Princess Consort, not Queen, when the Prince of Wales becomes King, Clarence House has said.
Charles and Camilla will marry on 8 April in Windsor
Mrs Parker Bowles' wishes were enough and legislation would not be needed on the issue, communications secretary Paddy Harverson said.
Ministers have said that Mrs Parker Bowles would be entitled to be known as Queen unless the law were changed.
The couple are to marry at Windsor Guildhall on 8 April.
"Legislation would only be required if it was deemed necessary to confirm formally that she should not have the title and status of Queen," said Mr Harverson
The government agreed she could choose the title of Princess Consort, Mr Haverson added.
'Less than frank'
On Monday Labour MP Andrew McKinlay had accused Prince Charles of being "less than frank with the country" over the issue.
"He [Prince Charles] knows that it was established in 1936 that the King's spouse automatically becomes Queen unless there is a law passed to the contrary," McKinlay told BBC Radio 4:
"I think he is deliberately holding this wedding under the smokescreen of a general election."
Following Clarence House's announcement on Tuesday, the Thurrock MP said: "We are being asked to accept that the law is what they say it is. I don't accept that.
"They have missed the point. This is not a matter for them, it is matter for Parliament. Parliament is the custodian of the constitution."
The BBC's royal correspondent Peter Hunt earlier said the need for a new law was not considered pressing.
"Given the present monarch's rude health, legislative action may not be needed for many years," he said.
"Then, with a new King on the throne, Parliament could either grant the couple their declared wish that the King's wife be known as Princess Consort, or no action might be taken because, with the passage of time, the majority of the population would have come to accept the idea of a Queen Camilla."