S-Corp Rules: Eligibility, Elections, and Termination

S corporation rules set out who can elect this tax status, who can own the shares, how the stock has to be structured, what the company must file, and what will end the election. An S corporation passes its income, losses, deductions, and credits through to shareholders, who report everything on their personal returns instead of the company paying a separate corporate tax.¹ The trade-off for that treatment is a set of eligibility limits under Subchapter S that are stricter than most business owners expect, and staying qualified means watching all of them at once.

Which Businesses Can Elect S-Corp Status

The company has to be a domestic corporation, meaning one organized under the laws of a U.S. state, territory, or the federal government.² Foreign-incorporated entities are out no matter where they do business.

A few categories of domestic corporation are also permanently disqualified because they already have their own tax regimes that conflict with pass-through treatment:

Financial institutions that use the reserve method of accounting for bad debts
Insurance companies taxed under Subchapter L
Domestic international sales corporations (DISCs) and former DISCs

Who Can Own the Shares

An S corporation can have no more than 100 shareholders.³ That cap is more generous than it looks, because the Code treats all members of a family as a single shareholder. Family here means a common ancestor, all lineal descendants of that ancestor, and any spouses or former spouses of those people, with the common ancestor no more than six generations removed from the youngest generation of family shareholders.⁴ A multigenerational family business with dozens of individual owners can still count as one shareholder under this rule.

Not everyone is allowed to hold the stock. Permissible shareholders are U.S. citizens and residents, certain estates, and qualifying trusts. Corporations, partnerships, and nonresident aliens cannot own shares.³ If an ineligible person acquires even one share, the S election terminates automatically on the date of the transfer.

Trusts That Qualify

Two trust types are specifically designed to hold S-corp stock. A Qualified Subchapter S Trust (QSST) must have a single lifetime beneficiary, and all of the trust’s ordinary income must be distributed to that beneficiary each year; the beneficiary is then treated as the owner of the shares for tax purposes. An Electing Small Business Trust (ESBT) is more flexible, allowing multiple beneficiaries with no requirement to distribute income currently. Both types require a formal election with the IRS. Grantor trusts and testamentary trusts that receive S-corp stock through an estate also qualify, but only within limited time windows.

The One Class of Stock Rule

An S corporation can have only one class of stock.² The rule looks at economic rights, not voting rights. Issuing both voting and nonvoting common shares is fine. What isn’t allowed is giving some shares a bigger claim on distributions or liquidation proceeds; the IRS treats that as a second class of stock, and the election is invalid.³

Loans can create the same problem if they behave more like equity than debt. The Code provides a safe harbor for “straight debt,” meaning a written, unconditional promise to pay a fixed amount on demand or on a specific date, with a fixed or variable interest rate that isn’t tied to the company’s profits. As long as the creditor is someone who could be a shareholder and the debt has no conversion feature, the IRS won’t reclassify it as a second class of stock.

How to Make the Election

A corporation elects S-corp status by filing IRS Form 2553, “Election by a Small Business Corporation.”⁵ The form asks for the corporation’s legal name, address, EIN, date of incorporation, and number of shares issued. Every shareholder must personally consent, providing a name, address, taxpayer identification number, the number of shares held, and the date those shares were acquired.⁶ You also pick a tax year. Most S corporations use a calendar year ending December 31, though other tax years are possible if you can show a business purpose.

Filing Deadline

Form 2553 must be filed no more than two months and 15 days after the start of the tax year you want it to take effect, or at any time during the preceding tax year.⁵ For a calendar-year corporation seeking S status starting January 1, 2026, the deadline is March 15, 2026. Miss it and the effective date shifts to January 1, 2027.

Form 2553 goes to one of two IRS service centers based on the corporation’s principal place of business. The current addresses and fax numbers are on the IRS site.⁷

Confirmation and Late Relief

After the IRS processes the form, it mails a CP261 notice confirming the election was accepted.⁸ Keep that notice permanently; it’s the document banks and auditors will ask for.

If you missed the deadline, relief is available under Revenue Procedure 2013-30 as long as the missed filing was the only thing that disqualified you, there was reasonable cause, and both the corporation and all shareholders reported income consistently with S-corp treatment. The request has to be made within three years and 75 days of the intended effective date.⁹ Past that window, you’ll need to request a private letter ruling and pay a user fee.

Paying Yourself: The Reasonable Compensation Rule

Most S-corp tax disputes start here. Unlike sole proprietors and partners, S-corp shareholders don’t owe self-employment tax on their share of business profits. Only the salary the corporation pays them is subject to Social Security and Medicare taxes; distributions of remaining profits are exempt from payroll tax.

That gap creates an obvious temptation: pay yourself a small salary and take everything else as a distribution. The IRS knows the incentive and looks for it. If your salary is unreasonably low for the work you actually perform, the IRS can reclassify distributions as wages and bill the corporation for unpaid payroll taxes, interest, and penalties.

There is no single formula for reasonable compensation. The IRS and the courts look at your training and experience, the time you devote to the business, what non-shareholder employees earn for comparable work, what similar companies pay for similar roles, and whether the corporation has a pattern of minimal salaries alongside large distributions. Pay that falls well below the market rate for the same job at a comparable employer is the fastest way to draw scrutiny.

The Qualified Business Income Deduction

S-corp shareholders who receive pass-through income on a Schedule K-1 are eligible for the Section 199A qualified business income deduction, which was made permanent by the One Big Beautiful Bill Act signed in July 2025. Eligible owners can deduct up to 20% of their qualified business income, whether they itemize or take the standard deduction. The deduction does not apply to W-2 salary the S corporation pays, to investment income, or to income earned outside the United States.

Starting in 2026, shareholders with at least $1,000 in QBI who materially participate in the business are guaranteed a minimum $400 deduction even if the standard 20% calculation would produce less. Above certain income thresholds, the deduction phases out for owners of specified service businesses such as law, medicine, and consulting. The income limits are adjusted annually for inflation.

Annual Filings

Every S corporation files Form 1120-S, the annual information return, by the 15th day of the third month after its tax year ends. For calendar-year corporations that’s March 15, shifted to the next business day when it falls on a weekend or holiday. The corporation also has to issue a Schedule K-1 to each shareholder by the same date, reporting that shareholder’s share of income, deductions, and credits.¹⁰ Shareholders use the K-1 to complete their personal returns.

Form 7004 grants an automatic six-month extension to file Form 1120-S, but it does not extend the time to pay taxes owed and does not postpone the K-1 delivery obligation. Late K-1s ripple straight into shareholders’ personal filings.

The penalty for filing Form 1120-S late is $255 per shareholder for each month or part of a month the return is overdue, up to 12 months.¹⁰ An S corporation with 10 shareholders that files a single day late owes $2,550. Six months late, the same corporation owes $15,300. The per-shareholder figure adjusts periodically for inflation.

How the Election Ends

S-corp status ends in one of two ways. The shareholders can revoke it, or the corporation can trip a disqualifying rule and lose it involuntarily.

Voluntary Revocation

Shareholders holding more than half the corporation’s stock can revoke the S election at any time by filing a revocation statement with the IRS.¹¹ Timing controls the effective date. A revocation filed on or before the 15th day of the third month of the tax year (March 15 for calendar-year corporations) takes effect retroactively to January 1 of that year. Filed after that date, it takes effect January 1 of the following year. The revocation can also specify a future effective date.

Involuntary Termination

The election terminates automatically the moment the corporation stops qualifying as a small business corporation. Common triggers are an ineligible shareholder acquiring stock, issuing a second class of stock, or exceeding 100 shareholders.¹¹ Termination takes effect on the date of the disqualifying event, not at year-end, which means the corporation may have a split year with part of it taxed as an S corporation and part as a C corporation.

A less obvious trigger applies to corporations that once operated as C corporations. If the company has leftover accumulated earnings and profits from that C-corp period, and passive investment income (rents, royalties, interest) exceeds 25% of gross receipts for three consecutive years, the election terminates at the start of the fourth year.¹¹

The Five-Year Waiting Period

After any termination or revocation, the corporation generally cannot re-elect S-corp status for five tax years. The IRS can waive that restriction if the corporation shows a significant ownership change (more than 50% of the stock changing hands) or that the termination was inadvertent and corrected quickly. A waiver requires a private letter ruling and the associated fee.

Built-In Gains Tax After a C-Corp Conversion

A corporation that converts from C-corp to S-corp status does not get a clean slate on unrealized appreciation. If the corporation sells an asset within five years of the conversion and the gain was built in at the time of the switch, it owes a corporate-level tax on that gain at the highest corporate rate, currently 21%.¹² The shareholders still report the income on their personal returns, but the corporate-level tax hits first. A C corporation sitting on highly appreciated real estate, intellectual property, or a valuable business line should plan the timing of any sale carefully around the S-corp conversion date. Once the five-year recognition period closes, appreciated assets can be sold without the built-in gains tax.

1
Office of the Law Revision Counsel. 26 U.S.C. 1366 – Pass-Thru of Items to Shareholders
2
Office of the Law Revision Counsel. 26 U.S.C. Subchapter S – Tax Treatment of S Corporations and Their Shareholders
3
Internal Revenue Service. S Corporations
4
Office of the Law Revision Counsel. 26 U.S.C. 1361 – S Corporation Defined
5
Internal Revenue Service. Instructions for Form 2553 – Election by a Small Business Corporation
6
Internal Revenue Service. Form 2553 – Election by a Small Business Corporation
7
Internal Revenue Service. Where to File Your Taxes for Form 2553
8
Internal Revenue Service. Understanding Your CP261 Notice
9
Internal Revenue Service. Late Election Relief
10
Internal Revenue Service. Instructions for Form 1120-S
11
Office of the Law Revision Counsel. 26 U.S.C. 1362 – Election, Revocation, Termination
12
Office of the Law Revision Counsel. 26 U.S.C. 1374 – Tax Imposed on Certain Built-In Gains