What is Form 1120-S (S-Corp Annual Return)?

Form 1120-S is the annual information return for S-corporations. Unlike Form 1120 (which reports and pays corporate income tax), Form 1120-S is informational — the S-corp pays no federal income tax. Instead, each shareholder's share of income, deductions, and credits is reported on a Schedule K-1, and shareholders report these items on their personal Form 1040.

**Filing deadline**

- Calendar-year S-corps: 15 March (the 15th day of the 3rd month after year-end) - This is one month EARLIER than the C-corp deadline, to give shareholders time to receive their K-1s and prepare personal returns - 6-month automatic extension via Form 7004 (to 15 September)

The extension covers the return only. If the S-corp owes built-in gains tax (from converting from a C-corp) or LIFO recapture, those taxes are due by the original deadline.

**Schedule K-1 distribution**

The company must furnish each shareholder's K-1 by the due date of the return (including extension). Shareholders cannot accurately file their personal Form 1040 until they receive their K-1. Late K-1s cascade into late personal returns — a reason many S-corp owners request personal return extensions.

**Late filing penalty**

$235 per month (or partial month) per shareholder, up to 12 months. A 5-shareholder S-corp filed 2 months late faces: $235 × 5 × 2 = $2,350 penalty.

**S-corp election timing**

To be treated as an S-corp for a given tax year, Form 2553 must be filed: - By the 15th day of the 3rd month of that tax year (March 15 for calendar year), OR - At any point during the preceding tax year

Late elections can be granted by the IRS for reasonable cause. A new company must file within 2 months and 15 days of formation to be effective for the year of formation.

**Shareholder basis tracking**

Shareholders must track their 'basis' in S-corp stock (starting basis + income allocations - loss allocations - distributions). Losses can only be deducted to the extent of basis. Distributions in excess of basis trigger capital gain. Tracking basis is the shareholder's responsibility — the 1120-S does not compute it.