Income tax return 7

respected experts pease provide resolution to the query.
a society registered u/s 12a has received donation which have been properly shown under schedule VC and the exemption u/s 12a has been properly availed by filling all the relevant point of return. yet notice u/s 143 (1)(a) for a.y. 2019-20 is issued stating " Voluntary contribution other than corpus is taxable if you have not claimed exemption or exemption claimed is not available". all the relevant schedule have been filled kindly help what should be done in response of it.