As per Section 17(5) (fa) of CGST Act, ITC is Blocked for goods or services or both received by a taxable person, which is used or intended to be used for activities relating to his obligations under Corporate Social Responsibility referred to in section 135 of the Companies Act, 2013
The amendment is effective from 1.10.2023.So ITC can be availed for prior period
In Income tax also CSR expenses is not allowed as business expenses.