Fewer than one in four eligible married couples have applied for an allowance that could reduce their tax bill by up to £220 a year, HMRC figures show.
The slow take-up is understood to be a source of great frustration at HMRC, which has promoted the scheme extensively on consumer websites and in national media.
Jane Ellison, the financial secretary to the Treasury, said just over 1 million couples in the UK had taken advantage of the tax break since its launch in April last year, out of 4.2 million who are eligible.
The figures came in a written response to a question in the House of Commons from the Liberal Democrat leader, Tim Farron.
A HMRC spokesperson said: “We are stepping up our marketing campaign to ensure couples do not to miss out on this marriage tax break. Couples have up to four years to claim backdated annual allowances and we have simplified the application process so that families do not miss out.”
Taxpayers who are married or in a civil partnership are eligible for the tax break if they have an income under £11,000 and their partner’s income is between £11,001 and £43,000.
Farron said the slow take-up showed his party had been right to voice doubts about the scheme while in the coalition government.
“When the Conservatives demanded to introduce their allowance, Liberal Democrats said that it was a needless gimmick,” he said. “These figures show that their plan is indeed a pathetic failure.
“Unsurprisingly, it turns out that people don’t choose to get married in order to secure a tax break. Rather than spending taxpayers’ cash trying to promote their flop, the Tories should abandon the policy and put the money into something useful.”
In 2013 the Lib Dems said they had agreed to the tax breaks in exchange for free school meals in primary schools, a policy championed by the then deputy prime minister, Nick Clegg.
“Liberal Democrats in coalition chose to spend our time fighting to give hot, healthy meals to young children, not on gimmicky giveaways,” Farron said. “Now the Tories are governing alone, it’s time they too started trying to do some good rather than clinging to half-baked ideas like the [marriage] allowance.”
