Dear Vinay,
Bonus is payable under the Payment of Bonus Act,1965 to the employees depending on the eligibility of their threshold salary u/s 2(13) and it has to be calculated and paid as a percentage of the total salary earned if they have worked for not less than 30 working days in any accounting year. Lock down is a period of no-employment analogous to lay off. Therefore, if any compensation received by the employees during lock down has to be added to the wages earned in the accounting year for the purpose of statutory bonus. If no wages or compensation is paid by the employer during the period of lock down, that is a different issue. In such a situation, bonus becomes payable on the actual salary received in the accounting for the remaining period.