The Council of Trade Unions says the time will come when workplaces are forced to reveal employee pay rates.
The Equal Employment Opportunities Commissioner plans to draft a parliamentary bill that would give employees the ability to compare how much they and their colleagues earn.
CTU president Helen Kelly says there's a growing pay gap between men and women, and the proposed bill would be the easiest way of giving women peace of mind about the monetary value of their work.
She says pay rates in many sectors are already widely known because employees in major industries are usually covered by a collective agreement with a union.
Problems will arise, she says, once any law is finalised and some women discover that they are underpaid; but the proposed bill is a "very good start".