minimum bonus means that employer will have to pay atleast 8.33% of worker salary or rs.100 whichever is higher as a bonus. This is the minimum amount as bonus which employer has to pay to his worker whether he had any allocable surplus or not during the accounting year . Now if the worker is less than 15 yrs old then the rule will be change slightly that is.. the minimum amount as bonus will be 8.33% or Rs.60 which ever is higher.
maximum bonus means if employer has enough allocable surplus then he cannot pay more than 20% of such worker salary as bonus.
In a nutshell employer is bound to pay his worker atleast some bonus even if the employer has no surplus similarly if employer has too much surplus then he cannot pay extra bonus to his workers as well.
SEC 15 says that if there is any allocable surplus after the payment of maximum bonus (which is 20% of salary of worker) then such extra surplus to be carryforward next to the accounting year ... upto 4 yrs can be done. This excess surplus which is carryforward is to be utilised for bonus payment only (as per 4rth schedule) . Like wise deficiency (due to low surplus) is to be carry forward in case of minimum bonus (Sec 10) upto 4 years.