The benefit of 80C is not available if income tax return is filed after the due date is a misconception
As per existing provisions of Section 80AC of the Act, no deduction was admissible under section 80-IA or section 80-IAB or section 80-IB or section 80-IC or section 80-ID or section 80-IE, unless the return of income by the assessee was furnished on or before the due date specified under Section 139(1).