In September, David Cameron announced his long-promised £700 million plan as a means of bolstering the institution of marriage. It will come into effect in 2015 and enable lower earners to transfer up to £1000 of their unused tax allowance to their spouse.
The Prime Minister has defended the plan, describing marriage as "an institution that helps to build a strong society" and said the UK Government should "properly recognise that in the tax system".
Jeremy Hunt, the UK Health Secretary, has also defended the tax break policy, saying it showed marriage was "special". But the policy has been widely criticised, including by Deputy Prime Minister Nick Clegg.
Yesterday, Eilidh Whiteford, the SNP's work and pensions spokeswoman, pointed to analysis by the UK Women's Budget Group, which showed only 15% of those who would benefit directly from the £200 a year bonus would be women as men were more likely to be the higher earner.
She said: "The UK Government marriage tax break is short-changing women.
The Women's Budget Group has recognised it will dissuade women from going back to work because the husband could lose their allowance if his wife gets a job that takes them over the earnings threshold."