Nearly all companies required to submit their gender pay gap figures to the Government have now done so, hours before the deadline.
By Wednesday an estimated 9,000 companies and public bodies with 250 employees or more must have submitted their median and mean gender pay gap data to the Government Equalities Office.
As of 4pm on Tuesday, figures show that 8,330 have done so, with 78% of those having a pay gap.
The rest of the employers either have no median gender pay gap (8%) or one in favour of women (14%).
Companies who do not provide their figures will face legal action including court orders and fines, but only after they have been given a month’s grace to report the figures.
The Equality and Human Rights Commission (EHRC) said they will write to employers who have not complied on April 9, giving them 28 days to publish the figures “before an investigation takes place and an unlawful act notice is issued”.
Courts can impose an unlimited fine on those who do not comply.
Chief executive of the EHRC Rebecca Hilsenrath said: “This is not optional; it is the law and we will be fully enforcing against all companies that do not report.
“This legislation is in place to bring about better gender equality in the workplace and any employer not complying needs to ask themselves tough questions, re-think their priorities, be prepared for serious reputational damage, and be ready to face a very unhappy workforce.”
Ryanair is the best-known company in the top 10 of those with the worst gender pay gap.
The airline pays women 71.8% less than men on average – when comparing median hourly rates, for every £1 men earn, women earn just 28p.
It says the disparity is because of the number of UK pilots it employs – 546 are male and only eight are female.
Of the 353 councils in England, 322 have reported their gender pay gap figures.
North Hertfordshire District Council has the worst median gender pay gap, paying women 34% less than men on average, with 25 councils having no gap.
Of the Premier League football clubs, West Bromwich Albion has the highest median gender gap, of 34.3%, with Manchester City having the highest in favour of women, paying them 17.2% more than men on average.
A spokesman for the Institute for Fiscal Studies said: “The gender wage gap has barely fallen over the last fifteen years and greater understanding of its determinants are needed.
“The new data being provided by employers could help contribute to that. As ever, however, the statistics are limited and need to be interpreted with care.”
The gender pay gap is calculated as the difference between the average salaries of men and women – it is not the same as equal pay, where firms are required to pay people doing the same job the same salary regardless of gender.
The national median gender pay gap is 18.4%.