Businesses with 100 employees or more should publish their gender pay gap data, according to a group of MPs.
Labour’s Stella Creasy will present a bill in Parliament on Tuesday, calling for the change in the threshold.
The law would also introduce mandatory ethnicity pay reporting and allow women to ask to see data if they suspect a disparity.
Ms Creasy said: “There has never been a more important time to really get to grips with this inequality.
“Equal pay legislation was brought in before I was born and we still don’t have equality. I don’t want my daughter still facing the same questions.”
The Equal Pay Implementation and Claims Bill (EPIC) 2020 has cross-party backing.
Signatories for the law include from the Tory chair of the Women and Equalities Committee, Caroline Nokes; the Liberal Democrats’ Christine Jardine; the SNP’s Anne McLaughlin and the Green Party’s Caroline Lucas.
When the issue was discussed in the Commons in 2018, the-then Minister for Women, Tory MP Victoria Atkins, said the government wanted “a foundation of data before considering whether or how to change the current requirements”.
She told MPs: “Let us have a couple of years of reporting at the higher level and with big companies, which have human resources departments that can deal with this, with the hope that it trickles down… to smaller employers as well.”
The gender pay gap is the difference between the average earnings of men and women.
From 2017, any organisation with 250 or more employees had to publish specific figures about their gender pay gap on their website, and report the data to the government.
Employers that fail to report on time or report inaccurate data are be in breach of the regulations and risk court orders and fines.
The annual April deadline was suspended this year due to coronavirus – but it is unclear when enforcement will be reintroduced, with a decision expected to be taken closer to the 2021 deadline.
Figures from the Office for National Statistics (ONS) showed in the year to April 2019, the gender pay gap for full-time workers rose to 8.9%
But for people under 40, the gap for full-time employees was close to zero.
In the proposal, Ms Creasy and her supporters are calling for a number of new measures to be introduced alongside the rise in the threshold.
Ms Creasy said she knew there needed to be a balance when it came to tackling the issue, especially amidst the current crisis.
But the Labour MP said coronavirus was showing why Parliament needed to act, with “more mums being made redundant and furloughed than their male counterparts”.
She added: “While women first started asking about equal pay in 1883, they still don’t have it. We have started the conversation and now we need action.
“It is better for everyone in society when we go to work with a fair wage.”
The Institute of Directors says real progress has been made in tackling the gender pay gap in recent decades but eradicating it entirely requires action across society, not just from employers.
In its submission to a 2018 parliamentary inquiry into gender pay, the business group said compulsory reporting had “associated consequences” for certain businesses.
“While reporting will sharpen companies’ focus on actions they can take, it also may, by implication, scapegoat employers for gender disparities which stem from wider societal issues over which they have little to no control,” it said.
The Equal Pay Implementation and Claims Bill (EPIC) 2020 from Ms Creasy is a Ten Minute Rule Bill – a procedure that lets backbench MPs make their case for a new law in a speech lasting up to ten minutes.
But as they are not proposals made by government, they often fail to make their way through Parliament to become law.