allowable expenses

only GST interest is allowed GST fee has penalty in nature and penalty paid in any tax regime is disallow under section 37(1)

Explanation 1 of Section 37, Explanation 1.—For the removal of doubts, it is hereby declared that any expenditure incurred by an assessee for any purpose which is an offence or which is prohibited by law shall not be deemed to have been incurred for the purpose of business or profession and no deduction or allowance shall be made in respect of such expenditure.

as per section 43 B any payment of taxes is allowed only on payment basis

good clarification and information