6.1 S-Corp Election and Tax Reporting

Module Overview

When a corporation is formed, it is classified by default as a C corporation for tax purposes. An S corporation refers to a corporation that chooses to be taxed under Subchapter S of the Internal Revenue Code, specifically Sections 1361–1379. This election allows the corporation to be treated as a pass-through entity for federal tax purposes. A C corporation pays tax on its profits, and shareholders may also be taxed on dividends received. In contrast, an S corporation does not pay federal income tax at the corporate level; its income, losses, deductions, and credits are passed through to shareholders, who report these items on their individual tax returns, whether or not the corporation distributes cash or property. This section outlines key topics related to S-corp formation, the process of making an S-corp election, taxation as a pass-through entity, entity-level taxes, loss limitation rules, and shareholder stock basis and debt basis.

Corporate Formation and S-corp Election

The general rule governing the formation of a corporation applies regardless of whether the corporation elects S corporation status. By default, any newly formed corporation is treated as a C corporation for federal tax purposes, and this classification is automatic unless a valid S corporation election is made with the IRS. The foundational rules for organizing, contributing property, and structuring ownership are the same at the point of formation; the election to be taxed as an S corporation is a separate process that only affects how the entity is taxed, not the underlying legal formation itself.
The shareholder’s basis in the newly issued S corporation stock is equal to the basis they had in the contributed property, increased by any cash also contributed and decreased by any liabilities assumed by the corporation as part of the transaction. The S corporation, in turn, takes a carryover basis on the property received, meaning its basis is the same as it was in the hands of the contributing shareholder.

Eligibility Requirements for S Corporation Status (IRC § 1361)

S corporations are designed for small businesses and closely-held companies, and there are strict eligibility requirements that must be met to qualify for S status. To be considered a “small business corporation” and to maintain S corporation status, a corporation must adhere to the following primary requirements:

• Domestic Corporation: The corporation must be organized in the United States or under federal or state law. Certain LLCs may also elect S status if they first choose to be taxed as a corporation. Foreign corporations are not eligible.
• Permitted Shareholders: Only U.S. citizens or residents, specific types of trusts, estates, or tax-exempt organizations may be shareholders. Partnerships, other corporations, and non-resident aliens cannot own S corporation stock, which keeps ownership simple and domestic.
• Number of Shareholders: The corporation may not have more than 100 shareholders. Family members and their estates are treated as one shareholder for this limit, supporting family-owned business structures.
• Single Class of Stock: The corporation must have only one class of stock with equal economic rights. All shares must provide the same rights to distributions and liquidation proceeds, although voting rights may differ. Creating a second class of stock, such as through preferential distribution rights, will disqualify S status.
• Eligible Entity Types: Certain corporations, including banks using the reserve method for bad debts, insurance companies subject to special tax rules, and DISCs, are ineligible for S status.

Corporations that meet these criteria are considered eligible small business corporations and must maintain compliance to preserve S status.

Election and Termination of S-Corporation Status (IRC § 1362)

Qualifying as an S corporation does not happen automatically. The corporation must affirmatively file Form 2553, Election by a Small Business Corporation, with the IRS. All shareholders at the time of election must consent to S status by signing the form or a consent statement.

Timing of the Election: To be effective for the current tax year, Form 2553 must be filed by the 15th day of the third month of that tax year (March 15 for calendar-year corporations). Filing by this deadline allows S corp status to take effect retroactively for the entire year. For example, to have S corp status for all of 2025, a calendar-year corporation must file by March 15, 2025.
If the election is filed late or if required shareholder consent is missing, S status becomes effective on the first day of the following tax year. For instance, an election filed in June 2025 would be effective January 1, 2026, unless late-election relief is granted.

Conditions for a Current-Year Election: Both of the following conditions must be met for the election to be effective for the current year: the corporation must meet all eligibility requirements for every day of the year before the election is filed, and every shareholder during that period must consent to the election. If either condition is not met, the election will not take effect until the following year.

Effective Date for New Corporations: For a newly formed corporation, the first tax year begins when the corporation has shareholders, acquires assets, or begins business. The election deadline is 2½ months after that date. For example, a corporation that begins business on June 10 would have a deadline in late August. An S election made before the corporation is officially formed is invalid.
Once made, the S election remains in effect until it is either voluntarily revoked or automatically terminated.

Timeline for S corporation election effective dates: Filing by March 15 means S status is effective for that year; filing after the cutoff defers effectiveness to the next tax year.

After taking effect, the S corporation election may be terminated either voluntarily by shareholders or involuntarily if eligibility requirements are not met. If S status is lost, the corporation is taxed as a C corporation.

• Voluntary Revocation: Shareholders holding more than 50% of the stock (including non-voting shares) may revoke S status by filing a statement with the IRS. A revocation by March 15 is effective for the entire tax year; otherwise, it may take effect later in the year or in the next year.
• Failure to Meet Requirements (Inadvertent Termination): If the corporation fails to meet any eligibility requirement, S status automatically terminates on the date of the violation. Common causes include exceeding 100 shareholders, an ineligible shareholder acquiring stock, or issuing a second class of stock. The termination is effective on the date of noncompliance, and the corporation must file two short-year tax returns.

The IRS may grant relief for inadvertent terminations if the error is corrected quickly and was not intentional. For example, if a shareholder agreement unintentionally creates a second class of stock but no improper distributions occur, the corporation can correct the agreement and seek IRS approval to maintain S status. Corporations must monitor stock transfers and governance to avoid inadvertent terminations.

• Excess Passive Investment Income: When an S corporation has accumulated earnings and profits from prior C corporation years, and more than 25% of gross receipts are passive investment income for three consecutive years, S status terminates on the first day of the fourth year. Passive investment income includes rents, royalties, dividends, interest, and similar receipts; however, rents derived from an actively managed rental business are excluded from the definition of passive investment income for this purpose. This rule prevents the sheltering of old C corporation profits in an S corporation. The termination is retroactive to the start of the year following the third consecutive high passive income year.

If S status is terminated, the corporation must usually wait five years before re-electing S status, unless the IRS waives this rule for inadvertent and corrected terminations. The post-termination transition period (PTTP) allows certain S corporation attributes to be used after termination, such as distributing previously taxed earnings or using suspended losses, typically for the year following termination or until the final S return is due.

S-Corp Tax Reporting

Federal Income Tax Exemption and Special Entity-Level Taxes

Generally, under IRC § 1363(a), an S corporation is exempt from corporate income tax and passes income or loss to shareholders, who report it on their individual returns and pay tax at their own rates. This system ensures a single level of tax on corporate earnings.

However, certain circumstances can result in entity-level tax:

• Built-in Gains Tax (§ 1374): When a C corporation converts to S corporation status holding appreciated assets or unrealized income, it is subject to a corporate-level tax (currently 21%) on built-in gains recognized during its first five years as an S corporation. The total gain subject to this tax over the five-year recognition period is  capped at the entity’s Net Unrealized Built-In Gain (NUBIG) measured on the exact date of conversion. The taxable net recognized built-in gain each year is calculated by netting the year’s recognized built-in gains and losses. However, this taxable amount cannot exceed the S corporation’s total taxable income for the year (computed as if it were still a C corporation). If the net recognized built-in gain exceeds this taxable income limitation, the untaxed excess carries forward to the next tax year within the recognition period. Once the five-year window expires, any remaining built-in gains can be realized without triggering this corporate-level tax.
• Excess Passive Income Tax: If an S corporation has accumulated earnings and profits from prior C years and passive investment income exceeds 25% of gross receipts, a tax of 21% is imposed on the excess net passive income. Continued high passive income for three years leads to termination of S status.
• LIFO Recapture Tax: If a C corporation using the LIFO inventory method elects S status, it must pay tax on the amount by which FIFO inventory value exceeds LIFO inventory value. The LIFO recapture tax is paid in four installments, starting with the final C corporation return and continuing with S corporation returns.

Except for these special cases, S corporations do not pay federal income tax at the corporate level. Shareholders are taxed on their share of the corporation’s income, whether or not distributions are made. Each shareholder’s tax liability is based on their share of S corporation earnings as reported on Schedule K-1, and they may need to make estimated tax payments accordingly. S corporations must also comply with payroll tax requirements, including issuing W-2s to shareholder-employees for salaries paid.

Allocation of Income and Loss to Shareholders (IRC § 1366)

All items of income, deduction, loss, and credit are allocated to shareholders pro rata based on ownership of the corporation’s stock. Each shareholder is taxed on their portion, determined by their percentage of shares and the length of time those shares were held during the year.

S corporation profit or loss is divided among shareholders according to the number of shares and days of ownership. If ownership remains unchanged, allocation is straightforward; for example, a shareholder owning 25% of the stock all year receives 25% of each item. If ownership changes during the year, items are allocated based on per-day, per-share ownership. For instance, if one person owns all shares for half the year and sells to another for the second half, each is allocated 50% of the year’s income. The daily proration method is used unless all shareholders agree to use an “interim closing of the books” method.

No Special Allocations: S corporations cannot allocate items disproportionately among owners. Every item is split according to each shareholder’s ownership, and all items retain their tax character. No shareholder can be allocated all of a particular tax credit or deduction; all receive their pro-rata portion. This requirement stems from the single-class-of-stock rule: equal economic rights mean no special allocations, as doing so would jeopardize S status.

Separately Stated Items: Certain items must be reported separately to shareholders because they can affect individuals differently. Schedule K-1 lists these items separately for each shareholder. Examples include long-term capital gains or losses, Section 1231 gains/losses, charitable contributions, interest income, dividends, investment expenses, foreign taxes, and tax credits. Each shareholder applies the proper tax treatment on their own return.

Example: If an S corporation has $100,000 of ordinary profit, a $5,000 long-term capital gain, and $2,000 of charitable contributions, and there are two shareholders each owning 50%, each receives $50,000 of ordinary income, $2,500 of capital gain, and $1,000 of charitable contribution. These items are separately stated on the K-1 for appropriate inclusion on individual returns.

This pro-rata allocation and reporting system ensures each shareholder annually pays tax on their share of S corporation results. Allocations are made with respect to the corporation’s tax year, usually ending December 31, and shareholders report pass-through items in their own tax year in which the S corporation’s tax year ends.

Tax Filing Requirements (Form 1120-S and Schedule K-1)

Most S corporations use a calendar year-end for tax purposes, unless a business purpose for a different fiscal year is established or requirements for a natural business year are met. The default tax year ends December 31. Corporations needing a different year-end must obtain IRS approval or qualify for an exception.

Each year, the S corporation reports income and tax details on Form 1120-S, U.S. Income Tax Return for an S Corporation. This return lists all income, deductions, and credits. Form 1120-S includes a Schedule K and individual Schedule K-1 forms for each shareholder, which summarize the shareholder’s share of various items. Each shareholder receives a Schedule K-1 to use on their personal tax return, and the corporation must file K-1s with the IRS.

The filing deadline for Form 1120-S is the 15th day of the third month after year-end: March 15 for calendar-year corporations. A six-month extension (to September 15) is available by filing Form 7004. Timely filing ensures shareholders receive K-1s for their personal tax reporting and helps avoid penalties.

While S corporations generally do not pay federal income tax, they may be subject to special taxes such as built-in gains or excess passive income taxes, and must make estimated payments if required. S corporations also have payroll tax and reporting obligations, including issuing Forms W-2 to employees and Forms 1099 to contractors or for taxable dividends.