Payment of bonus ammendment act 2015

SIR, 1. We already paid 20% bonus to our employees for the FY 2014-15 under wage ceiling of Rs.10000/-. Exgratia paid to our employees under wage ceiling of above Rs.10000/-. Now we will pay arrear bonus to our employees?. Exgratia adjust to bonus? Can 20% reverse to 8.33%? Will pay bonus to retire employee? kindly clear.