Since his basic and DA put together is less than Rs 21000, he is eligible to Bonus. But you can calculate the bonus payable on the minimum wages fixed by your state government. Suppose the minimum wages applicable to the same employment in your industry is Rs 12000, you can calculate his bonus as if his salary is Rs 12000. If yours is an organisation for which no minimum wages has been fixed by the government, then you can calculate bonus as if the salary is Rs 7000 per month.