Analysis of data from HM Revenue & Customs by law firm Clyde & Co has shown that although the number of higher-rate taxpayers has increased by 1m individuals over the past five years, women have accounted for 27 per cent each time.
Thus, while women made up 1.26m of the 4.64m higher-rate taxpayers last year, they made up 1.21m of the 4.47m in 2014/15, and so on.
Does that prove women are earning less than their male counterparts? A target set by Lord Davies last year aims for 33 per cent of FTSE 100 board members to be women by 2020, while several of the UK's largest banks have signed up for a voluntary charter which aims at getting more women into senior roles in the financial services industry.
Meanwhile, in July last year David Cameron unveiled rules requiring firms with 250 employees or more to publish information on the pay gap between men and women by April 2018.
So far, though, pay doesn't seem to be matching up. "It is clear the initiatives launched [by the government] so far have not had an impact on national figures for women in high-earning positions," said Heidi Watson, employment partner at Clyde & Co.
"[This], in turn, impacts on the national gender pay gap. While there are no penalties for breaching the rules, the risk of reputational damage is high. Some critics believe the rules lack teeth but the public scrutiny firms will face through 'naming and shaming' is likely to be intense."
"One of the most significant causes of the pay gap for most organisations is the lack of women in senior roles. If an organisation can crack this, they will be way ahead of their competitors. This data shows the impact of any current programmes is not yet being felt".