Wage Equity Act of 2021 This bill addresses workplace wage discrimination based on sex. Specifically, it limits the acceptable reasons for wage disparities based on sex to legitimate business-related factors unrelated to sex. It also protects from liability for such discrimination those employers who conduct a job and wage analysis audit to identify wage disparities and take reasonable steps to remedy any such disparities. Further, the bill prohibits employers from relying on, or requesting, the wage history of a prospective employee for hiring and wage determination purposes unless it is voluntarily provided by the prospective employee. Employers generally may not prohibit employees from inquiring about, or discussing, wage information concerning another employee or from requesting information from an employer about wage differentials. Finally, the bill permits the Department of Labor to establish a grant program for negotiation skills education for women and girls. It also requires the Government Accountability Office to study and report on the causes and effects of sex-based wage disparities.