LONDON • Thousands of United Kingdom employers are set to publish figures showing the difference between what men and women earn, under a law the government says is not only fair but could also boost the economy by billions.

Voluntary, private and public organisations with 250 or more employees will have to reveal gender discrepancies in staff pay by April next year. The new regulations came into force yesterday and will affect about 9,000 firms employing more than 15 million people - almost half the UK workforce.

The national pay gap stands at 18.1 per cent, the Office for National Statistics estimates.

Employers will publish figures from a "snapshot" period, calculating the median and mean pay gaps, the proportion of men and women in each quartile of the payroll and the gaps reflected in any bonuses - including the proportions of male and female bonus recipients. Companies will also be encouraged to publish "action plans" showing how to close any pay gaps.

"Helping women to reach their full potential isn't only the right thing to do, it makes good economic sense and is good for British business," Minister for Women and Equalities Justine Greening said in an e-mailed statement.

Eliminating gender gaps at work could add £150 billion (S$262 billion) to annual gross domestic product by 2025, according to a study by consulting firm McKinsey. The Fawcett Society, which campaigns for gender equality, says it would take 60 years to close the gap based on current progress.

Few big organisations currently report such data. Those that do include Enbridge, Microsoft Corp and Singapore Exchange, according to Bloomberg Intelligence.

BLOOMBERG