A study by the Ministry of Women's Affairs has found an income gap of up to 6% develops between men and women a year after they graduate from university with a bachelor's qualification.
The study used income data from Inland Revenue to examine differences in income for graduates, one year and five years after they enter employment.
Women's Affairs Minister Pansy Wong says the findings show a clear difference in income between men and women who graduate within the same fields of study.
The gaps vary from 1% for graduates in society and culture, to 20% after five years for those in management and commerce.
Last year, the Ministry received an extra $2 million over four years to address the gender pay gap.