Resigned Employees eligible for the variable pay on a prorated basis - worked for 4 months

Dear All, I would like to bring a prospect for a discussion.

There was a Senior management employee who joined a company and worked with it for about 4 months. His performance was found to be good, however, due to his interest in another sector of business. He has left the company. The company has agreed with him a salary along with variable pay (10% of Salary) at the time of his joining. During his tenure of 4 months, there was no KPI has been set, as he was under probation period. The employee has submitted his resignation on his third month of employment and served his notice period as per the terms agreed in the appointment order.

The point that arises here is does he eligible for the variable pay on a prorated basis or he is not eligible for such payment.

Since reportedly the agreement was for paying variable pay @ 10% salary, it is payable as the performance has been felt to be good. Framing of KPI is a management activity and that cannot be made as a reason for non-payment of variable pay.