The Election-Based Requirement

The obligation to file Form 1120-S stems from the S election itself, not from the level of business activity. Once a corporation files Form 2553 and the IRS accepts the S election, the corporation must file Form 1120-S every year until the election is terminated or revoked. A dormant S corporation with no revenue, no expenses, and no transactions is still required to file. The return reports income, deductions, and credits that pass through to the shareholders on their individual returns via Schedule K-1.

This pass-through reporting is the core function of the S corporation return. The entity itself generally does not pay federal income tax. Instead, each shareholder reports their proportionate share of the corporation’s income, losses, deductions, and credits on their personal return. But the information return is the mechanism by which those pass-through items are calculated and reported to both the IRS and the shareholders.

Penalties for Failure to File

The penalties for failing to file Form 1120-S are substantial and apply per shareholder per month. The penalty is $235 per shareholder per month (for 2024 returns), for up to 12 months. An S corporation with four shareholders that files six months late faces a penalty of $5,640. These penalties apply even when the corporation owes no tax and even when all shareholders have properly reported their income on their personal returns. The IRS assesses these penalties automatically, and abatement requests require demonstrating reasonable cause.

Schedule K-1 Obligations

The S corporation must issue a Schedule K-1 to each shareholder by the filing deadline, including extensions. The K-1 reports the shareholder’s allocated share of ordinary business income or loss, rental income, interest, dividends, capital gains, Section 179 deductions, charitable contributions, and numerous other items that affect the shareholder’s individual return. Errors or delays in K-1 issuance cascade into problems for shareholders who cannot complete their own returns without this information.

Built-In Gains and Other Entity-Level Taxes

While S corporations are generally pass-through entities, certain situations create entity-level tax liability. The built-in gains tax applies when a C corporation converts to S status and sells appreciated assets within five years of the conversion. Excess net passive income tax applies when the S corporation has accumulated earnings and profits from C corporation years and passive investment income exceeding 25% of gross receipts. The LIFO recapture tax applies in the year of conversion if the corporation used LIFO inventory methods as a C corporation. These taxes are reported and paid on Form 1120-S.