Filing the wrong income tax form or leaving mandatory schedules blank can result in an automated "Defective Return" notice under Section 139(9). When a return is flagged as defective, the department gives you a 15-day window to correct the mistakes. Failing to respond on time can result in your return being treated as invalid. Let's look at the main causes of these notices.

Common Reasons for Defective Notices

The automated validation engines flag returns based on several criteria:

1. Wrong ITR Form Selection: Filing using ITR-1 (for simple salaries) when you have business income, F&O trades, or foreign assets. This is the most common cause.
2. Missing Business Balance Sheet: Filing business returns (ITR-3 or ITR-4) but leaving mandatory fields like sundry debtors, creditors, or cash balance blank.
3. TDS Mismatches: Claiming a TDS refund when the corresponding income has not been declared in the return.

How to Resolve a Defective Return Notice

If you receive a notice, you must log into the e-filing portal within 15 days, navigate to the "Pending Actions" menu, and select "In response to notice u/s 139(9)". You can then upload a corrected tax return selecting the appropriate form (e.g., ITR-3 for trading income) to clear the defect.