| File | Topic |
|---|---|
| Chapter 01 - Tax Return Basics/form-1040-overview.md | Form 1040 Overview and Structure |
| Chapter 01 - Tax Return Basics/form-1040-sr.md | Form 1040-SR for Seniors |
| Chapter 01 - Tax Return Basics/who-must-file.md | Who Must File — Income Thresholds |
Key concepts: Filing thresholds by age and status, extension rules (Form 4868 extends filing but not payment), FTF and FTP penalties, sources of tax information (W-2, 1099, K-1), preparer due diligence, amended returns (Form 1040-X, 3-year lookback).
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