Which companies are required to undertake impact assessment?

Rule 8(3) of the Companies (CSR Policy) Rules, 2014 mandates following class of companies to conduct impact assessment:
(i) companies with minimum average CSR obligation of Rs. 10 crore or more in the immediately preceding 3 financial years; and
(ii) companies that have CSR projects with outlays of minimum Rs. 1 crore and which have been completed not less than 1 year before undertaking impact assessment.

Impact assessment shall be carried out project-wise only in cases where both the above conditions are fulfilled. In other cases, it can be taken up by the company on a voluntary basis.