Dear Questioner,
I think your question inherently comprises of two parts.The first part relates to disbursement of bonus along with usual terminal benefits to an employee who leaves the job once for all in the middle of an accounting year for which bonus is yet to be declared.The second part is about denial of bonus to such an employee merely because he leaves the job before the close of the accounting year and bonus declaration.Computation of bonus, in general, is relatable to the performance of the establishment during the accounting year; determination of the amount of bonus to each eligible employee, in particular, is based on his total earnings in that accounting year.Therefore, it is not necessary to include the amount of bonus tentatively in the terminal benefits immediately on termination during the middle of the accounting year when it is not computed. Of course, there can be a stipulation in the relieving orders that proportionate bonus would be paid soon after its declaration. Like Jagatkumar and Hardik said, youcan't deny bonus to an employee who is otherwise eligible to it for the mere reason of his termination of employment in the middle of the accounting year.
For recovery of bonus due from an employer, pl refer to section 21 of the Payment of Bonus Act,1965 which envisages an individual claim by an employee for denial of bonus due to him.