Form 1040 (US Individual Income Tax Return)

Detailed Explanation

Form 1040 is the master individual income tax return for US citizens and resident aliens. It captures total income from all sources, applies above-the-line adjustments to arrive at AGI, applies the standard or itemized deduction and the QBI deduction to compute taxable income, calculates regular tax, applies credits, adds other taxes (self-employment, AMT, NIIT, Additional Medicare), subtracts payments and withholding, and produces the refund or balance due. The 1040 is supplemented by numbered Schedules: Schedule 1 (additional income and adjustments), Schedule 2 (additional taxes including AMT and SE tax), Schedule 3 (additional credits and payments), and named schedules: A (itemized deductions), B (interest and dividends), C (self-employment), D (capital gains, with Form 8949), E (rental and pass-through K-1 income), and SE (self-employment tax). The return is due April 15 (or the next business day if April 15 falls on a weekend or holiday), with a six-month automatic extension to October 15 available via Form 4868. Important: Form 4868 extends the time to FILE, not the time to PAY. Any balance owed must be paid by April 15 to avoid interest and failure-to-pay penalties. Variants include Form 1040-SR (large-print version for taxpayers 65 and older), Form 1040-NR (nonresident aliens), and Form 1040-X (amended return, generally must be filed within 3 years of original filing or 2 years of payment to claim a refund).