The proportion of women high earners has not changed over the past four years, according to a new study.
Women accounted for just over a quarter of higher rate taxpayers in each of the last four financial years, research by law firm Clyde & Co found.
Last year, 1.1 million of the 4.47 higher rate tax payers were women, said the report - noting that initiatives have been launched to try to tackle the gender pay gap, such as requiring firms to publish any differences in pay between men and women.
Charles Urquhart, employment partner at Clyde & Co, said: "Over 40 years since we saw the first legislation aimed at tackling differences between the sexes in the workplace, these further initiatives, and the intent behind them, are welcome.
"We don't know yet precisely what figures employers will be required to publish, but if it's simply a matter of reporting an average of men and women's basic pay and bonuses every three years, it won't tell us much more than we already know.
"For gender pay reporting to be valuable, a like for like comparison across all levels within an organisation, from the chief executive to unskilled levels of employee, would be needed.
"This would be much more useful than average data across an organisation, but it would create far more of a burden on employers, which the Government will no doubt be wanting to avoid."