By Estelle Shirbon
LONDON (Reuters) - Plans by Conservative Prime Minister David Cameron to give tax breaks to some married couples drew criticism on Saturday that he was promoting a fantasy 1950s model of family life not corresponding to the realities of modern Britain.
Fulfilling a long-standing Conservative pledge to "recognize marriage in the tax system", Cameron has proposed that married couples in which neither spouse is a higher rate taxpayer should get breaks worth up to 200 pounds ($320) a year per couple.
If approved by parliament, the measure will come into force in April 2015, just one month before the next general election, and is expected to benefit some 4 million couples.
"All we're saying is that marriage is a good thing for our country - it's the ultimate form of commitment under the law - and we want to show our support for it," Cameron wrote in an article published in Saturday's Daily Mail newspaper.
The measure will also apply to same-sex couples in civil partnerships. From next year, same-sex couples will be able to marry under a new law passed by parliament in July.
"This summer I was proud to make equal marriage the law. Love is love, commitment is commitment," Cameron wrote.
The main opposition Labour party said the measure would benefit a minority of married couples to the detriment of other groups, and any benefit was outweighed by a range of welfare benefit cuts introduced by Cameron's government since 2010.
"He's so out of touch he thinks people will get married for 3.85 pounds a week," lawmaker Rachel Reeves said for the party.
Labour's deputy leader Harriet Harman took to Twitter to denounce possible consequences of Cameron's plan. "Married man's tax allowance will go to man on his third wife but not to first two wives looking after his children!" she tweeted.
A campaign group called Don't Judge My Family said the plan discriminated against widows and widowers, single parents, the one in four children whom it said grow up in single parent families, and unmarried cohabiting couples, among other groups.
"It's about promoting a fantasy 1950s family and won't go to many of the families who need support the most. In these tough times the government should be helping families, not judging them," the group said on its website.
The Conservatives pledged to recognize marriage and civil partnerships in the tax system in their 2010 election manifesto, but the idea was not enacted until now because it was opposed by their junior coalition partners, the Liberal Democrats.
Under the coalition agreement signed by the parties in May 2010, Lib Dem lawmakers will be able to abstain on a Conservative-backed bill introducing tax breaks for married couples without risking a break-up of the coalition.
Deputy Prime Minister Nick Clegg, the Lib Dem leader, once dismissed the Conservative plan as "patronizing drivel". ($1 = 0.6203 British pounds)
(Editing by Mark Heinrich)