The Council of Australian Governments Reform Council report, shows that young male dentists earn $14,000 more than women in their first job, while male architect graduates earn $9000 more and male lawyers $4300 more.
Women even earn 12 per cent less for non-managerial roles - $31 an hour compared to $35 for men.
In total, a woman working 40 hours a week in a non-managerial job will earn $8736 less than a man in a similar role.
Women earn 17.5 per cent less than men, on average - adding up to $266 per week.
And they retire $87,000 poorer, because women accumulate less superannuation over their working lives.
"Financial disadvantage starts as soon as women enter the workforce,'' the official report says.
"Graduate starting salaries are overall significantly lower for women than men.
"Lower pay and workforce participation means women are retiring with an average of 36 per cent less superannuation than men.''
The report shows girls are better prepared than boys to start school, and outperform them in English.
But boys trump girls at maths, a school subject which often leads to higher-paid jobs.
Gen Y women are better educated than men, who are less likely to have a university degree or diploma by the age of 30.
Nearly half of working women have part-time jobs, compared to one in six men.
COAG Reform Council chairman John Brumby said women in their 20s were part of the first generation to "pull ahead of their male peers'' in terms of post-school education.
"We have to ask ourselves why it is that girls do well in the education system, but once out in the employment market they have to fight to have their value realized,'' he said.
"The highly competitive global environment means we simply cannot afford to waste the talents and perspective of half our population.''