It’s Equal Pay Day, so congratulations, ladies! You’ve finally earned as much money as your male colleagues did last year, just after putting in four more months of work!

Or have you?

Last year, the average woman made 82 cents for every dollar the average man made — a disparity known as the gender pay gap, which the annual Equal Pay Day highlights. If you’re black or Latina, the gap is even wider, since you earn on average 63 cents or 54 cents to a man's dollar, respectively. (That’s according an analysis of 2017 U.S. Census data from the nonpartisan National Partnership for Women & Families.)

But since private-sector employees in the United States don’t usually know what their coworkers make, how can you be sure you’re “average”? Advocates say a lack of transparency about pay cripples the fight for equity: If you don’t know what your coworker is making, you can’t know if he’s getting paid more just for being a man.

“There’s still a lot of secrecy about what people make and how compensation is set,” explained Maya Raghu, director of workplace equality and senior counsel for the National Women’s Law Center. “Some of that is cultural. As a society, people generally don’t reveal what they make or talk about it. But it becomes a problem because pay discrimination isn’t easy to uncover.”’

The Equal Pay Act, which became law more than 60 years ago, made it illegal to pay women less than men for doing the same work. But no U.S. law requires private-sector companies to reveal how much they pay employees or why. And so the wage gap persists, perhaps because of differences in education and experience, or women’s saturation of lower-paying occupations, or the cost of childbearing, or sexism and racism.

Countries in Europe and elsewhere are using pay transparency laws to embarrass companies into ensuring they pay people equally. Australia and Germany want companies to publish reports on their pay gaps, and Iceland recently went a step further, enacting a measure that will force employers to prove they pay men and women equally — or face fines for every day they don’t comply.

The United Kingdom also now requires companies with more than 500 employees to publish information on their pay gaps. Corporations’ first reports were due last week, and the ensuing revelations — at Goldman Sachs, for example, British women make an average of 56 percent less than men — sparked the hashtag #PayMeToo.

“As #MeToo was starting to gain momentum, you saw some female celebrities come out and reveal they had been paid far less than their male counterparts,” said Diana Doukas, who served as director of the White House Business Council during the Obama administration. “So it became it kind of rolled into this women’s empowerment piece. And I hope that goes along with a level of being respected in a way that women should be in the workplace.”

While at the White House, Doukas helped recruit more than 100 companies to join the Equal Pay Pledge, a private-sector effort to fight pay discrimination. Those companies promised to analyze their pay schemes for gender bias annually and to find ways to curb implicit bias and structural barriers that hold women back. They did not have to reveal the results of their analyses; the pledge was also completely voluntary, lacking any mechanism for oversight or enforcement.

“We knew that for that work to continue, it would have to be continued outside of government and outside of the White House,” said Kalisha Dessources, former policy adviser to the Council on Women and Girls, an Obama-era initiative. “I think our biggest goal was just being at the White House and wanting to use that moment to get companies to make that commitment.”

In its twilight, the Obama administration did push for one more federal regulation aimed at increasing pay transparency: In September 2016, the Equal Employment Opportunity Commission started requiring businesses with at least 100 employees to hand over information about their workers’ compensation by race, gender, and ethnicity.

The commission would’ve received its first batch of information this March. But the Trump administration pushed pause on the initiative in August.

“It’s enormously burdensome,” Neomi Rao, administrator of the Office of Information and Regulatory Affairs, told the Wall Street Journal at the time. “We don’t believe it would actually help us gather information about wage and employment discrimination.”

That was cool with Ivanka Trump, who branded herself as a working woman’s champion and once called closing the gender pay gap “critical to the economic empowerment of American women.”

“Ultimately, while I believe the intention was good and agree that pay transparency is important, the proposed policy would not yield the intended results,” she said in a statement at the time. “We look forward to continuing to work with EEOC, OMB [Office of Management and Budget], Congress, and all relevant stakeholders on robust policies aimed at eliminating the gender wage gap.”

Several women’s rights organizations, including the National Women’s Law Center, have sued the administration over the rollback. A White House spokesperson referred a request for comment on any current efforts to close the pay gap to the Department of Labor.

“With nearly 3 million jobs created since Election Day 2016, President Trump is working to create jobs and raise wages for all Americans,” a spokeswoman for the agency said. “Average hourly earnings in March rose by 2.7 percent over the previous 12 months, and the 3-month average increase in earnings is the highest since 2009.”

Some of the companies that joined the Equal Pay Pledge say they’ve lived up to their promises anyway. VICE News asked the 28 companies that first signed the pledge, in June 2016, about their efforts to end pay inequity. Seventeen did not respond to emailed questions or requests for interviews. Of the 11 companies that did respond, 10 confirmed that they had conducted pay audits since signing the pledge. Several said they’d found that they paid men and women equally for the same jobs, had adjusted employees’ salaries when they discovered a wage gap, or found ways to cut down on bias when determining compensation. (It’s perhaps unsurprising that these companies’ findings were so sunny: If you have good news, why not share it?)

Only one company, American Airlines, confirmed that it had yet to conduct a pay analysis, which a spokesperson attributed to yearslong delays with a new human resources system.

“I think businesses are kind of rightfully worried about what happens to employee morale when all of a sudden their pay scales are being revealed,” said Jake Rosenfeld, a Washington University-St. Louis associate professor of sociology. “And without a government push, they’re not going to reveal that willingly.”

In a study of British workplaces, Rosenfeld found that transparency about workers’ salaries may help increase workers’ earnings. State laws that stop employers from asking about workers’ past wages or penalizing those who share their salaries could also help rein in pay disparity, Rosenfeld said, adding that the latter are associated with smaller gender wage gaps. But without more information, it’s hard to know for sure if such laws actually cause wage gaps to shrink.