Employers could face unlimited fines if they fail to comply with gender pay gap reporting regulations, the Equality and Human Rights Commission (EHRC) has warned.
After the deadlines pass - 30 March 2018 for public sector organisations and 4 April 2018 for businesses and charities - the EHRC has said it will give employers 28 days to become compliant.
Failure to meet requirements beyond this point could ultimately lead to a fine decided by courts, with no maximum limit.
Under the regulations, private and voluntary-sector employers with 250 or more employees are required to publish information about the difference between men and women's pay and bonuses.
However, many have yet to comply, as 3,755 out of 9,000 businesses have complied with reporting regulations so far.
Rebecca Hilsenrath, chief executive of the EHRC, said:
"The clock is ticking and with just 10 days to go, those who haven't reported really are entering the last chance saloon.
"This is not optional; it is the law and we will be fully enforcing against all companies that do not report."
Jemima Olchawski, head of policy and insight at the Fawcett Society, added:
"The gender pay gap represents a productivity gap.
"It's bad for women who lose out on potential earnings and career opportunities, but also bad for businesses who are failing to properly recruit, promote and reward women."
Talk to us about your reporting obligations.