Deduction 80C, 80D, 80TTA under old regime under belated return

Belated Return vs Due Date (Section 80AC)

Under Income-tax Act Section 80AC, deductions under Chapter VI-A (e.g., Sections 80C, 80D, 80TTA, etc.) are generally not allowed if the return is filed after the due date specified under Section 139(1). That means if you file a belated return (after the original due date for that year), the deductions under these sections cannot be claimed, even if you are otherwise eligible, unless specific rules allow otherwise.

Applicability to 80C, 80D, 80TTA

80C (investments like PPF, EPF, life insurance, etc.)
You generally cannot claim 80C deductions in a belated return that is filed after the original due date (Section 139(1)). This is due to Section 80AC restricting Chapter VI-A deductions with late filing.
80D (health insurance premiums)
Same principle applies — 80D cannot be claimed in belated returns filed after the due date.
80TTA (interest on savings account)
Although 80TTA is a small interest deduction, it also falls under Chapter VI-A and, by the same logic, cannot be claimed in a belated return that is filed after the due date.

Exceptions & Practical Clarifications

If the return is filed before the original due date (regular ITR), then all eligible deductions under 80C/80D/80TTA in the old regime can be claimed normally.
A belated return filed under Section 139(4) still allows compliance and possible refund claims, but Chapter VI-A deductions are typically disallowed if the return is late.

Workaround

If you have missed claiming deductions due to late filing, the only way to correct that is to have filed the return on time originally. You cannot resurrect Chapter VI-A deductions by just filing a belated return. (There is no provision for late proof submission that overrides the due-date requirement under Section 80AC.)