Women are effectively working for free for the rest of the year because of the gender pay gap, equality campaigners have said.
According to the Fawcett Society, it will take 60 years to close the gap at the current rate of progress.
Its report found that jobs women do are more likely to be low paid and they are less likely to receive a bonus or progress to the highest job in their organisation.
The society has called for more action from the Government and employers to tackle pay discrimination, job "segregation" and help to get women into senior posts.
To highlight the issue, Equal Pay Day is taking place this Thursday, and some companies are offering female employees the chance to leave early.
Labour leader Jeremy Corbyn has also lent his support to the issue.
He tweeted a picture of himself with other Labour figures holding posters with the caption: "Equal pay, Equal value".
Rebecca Hilsenrath, chief executive of the Equality and Human Rights Commission, said the scale of the disadvantages that working women face is "shameful".
"Girls and women outperform men at every stage in education, but time after time this success is not translated into rewards at work. Women are a vital part of the workforce and any proposals to tackle the gender pay gap must be strong enough to deliver the change everyone wants to see."
A Government spokesman said the UK now has the lowest gender pay gap on record but "we know there's more to do".
"That's why we are requiring employers to publish their gender pay and gender bonus gap for the first time from April and we are giving working parents up to 30 hours of free childcare from next September, meaning women can go back to work and progress in their careers after having children if they choose to," they added.