Less than a quarter of couples eligible for marriage tax allowance are bothering to claim it, according to HM Revenue and Customs
The allowance - introduced in April 2015 to incentivise marriage - is worth £220 in 2016/17
.
However those eligible can also back-date a claim for last year, meaning £432 can be claimed in total.
Out of 4.2m couples who could claim that amount, only 1m have done so, despite an HMRC advertising campaign.
Marriage tax allowance lets one half of a married couple transfer part of their tax-free allowance to their partner.
However one of the partners must not be earning more than £11,000 - the personal allowance - while the other must be paying income tax at the basic rate.
http://www.bbc.co.uk/news/business-37702190
Married Couple's Allowance
https://www.gov.uk/married-couples-allowance/overview