What Is an S Corporation (and Why Does It Matter)?

An S Corporation is a domestic corporation that has elected pass-through taxation under Subchapter S of the Internal Revenue Code. Income, losses, deductions, and credits flow through to shareholders, who report them on their personal tax returns. The corporation itself pays no federal income tax at the entity level.

The name comes directly from Subchapter S of the Internal Revenue Code — the section of tax law that governs this election. It's not a separate legal entity type the way an LLC is. An S corp starts as a standard corporation and then elects a different tax treatment by filing with the IRS.

Most small and mid-size businesses that choose the S corp structure do so because it avoids the double taxation that hits C corporations — once at the corporate level and again when shareholders receive dividends.

The S corp tax status matters because it changes how the business's income is taxed — and for many business owners, that difference adds up to real money. Instead of the corporation paying federal income tax and shareholders paying again on dividends, income passes through once and gets taxed only at the shareholder level.

For shareholders who also work in the business, there's an additional benefit. S corp owners who are employees must pay themselves a reasonable salary — which is subject to payroll taxes — but any remaining profit distributed beyond that salary is not subject to self-employment tax. That distinction is what makes the S corp structure attractive for profitable businesses.

The tax savings aren't automatic, though. The IRS pays close attention to whether S corp owner-employees are paying themselves a genuinely reasonable salary. Setting it too low to avoid payroll taxes is one of the most common mistakes that triggers IRS scrutiny.

To qualify for S corp status, a corporation must meet all of the following IRS requirements: it must be a domestic corporation, have no more than 100 shareholders, have only one class of stock, and have only eligible shareholder types. Missing any one of these disqualifies the election.

Here's what each requirement means in practice:

Domestic corporation: The business must be incorporated in the United States and conduct business here. Foreign corporations don't qualify.

Shareholder limit: No more than 100 shareholders. Members of the same family can count as a single shareholder under IRS rules, which gives family-owned businesses more flexibility than the number suggests.

Eligible shareholders: Individuals, estates, and certain trusts are allowed. Partnerships, other corporations, and non-resident aliens are not. This is the requirement that most often catches businesses off guard when they try to bring in outside investors.

One class of stock: All shares must carry the same rights to distributions and liquidation proceeds. You can have voting and non-voting shares, but you can't have preferred stock with different economic rights.

Ineligible corporations: Certain types of businesses — including insurance companies, financial institutions using specific accounting methods, and domestic international sales corporations (DISCs) — cannot elect S corp status regardless of whether they meet the other requirements.

S corporations offer real tax advantages and liability protection, but they also come with restrictions that don't apply to LLCs or C corporations. Whether the structure fits depends on your ownership situation and how you plan to grow.

Advantages of an S corporation:

No double taxation: Income passes through to shareholders and gets taxed once, at the personal level. C corporations pay corporate tax first, then shareholders pay again on dividends.

Potential payroll tax savings: Profitable S corp owner-employees pay payroll taxes only on their salary, not on distributions above that amount.

Liability protection: Like any corporation, an S corp separates personal assets from business debts and legal claims.

Easier ownership transfer: Shares can be transferred without disrupting the business's operations or tax status, as long as the new shareholder is eligible.

Trade-offs of an S corporation:

Ownership restrictions: The 100-shareholder cap and eligible-shareholder rules make it harder to bring in certain investors, including venture capital funds structured as partnerships.

One class of stock: You can't offer preferred shares with different economic rights, which limits how you can structure deals with investors.

IRS scrutiny on salaries: The IRS watches S corp owner-employee compensation closely. Getting the reasonable salary wrong can mean back taxes and penalties.

Ongoing compliance: S corps carry more administrative requirements than LLCs — payroll, corporate formalities, and annual filings all apply.

The S corp sits between an LLC and a C corporation in terms of structure and complexity. All 3 offer liability protection, but they differ significantly on taxation, ownership flexibility, and compliance requirements.

[object Object]

One thing worth knowing: an LLC can elect to be taxed as an S corporation without converting to a corporation. That's a separate IRS election and a different path than forming a corporation and filing Form 2553. A tax professional can help you figure out which route makes sense for your situation.

S corp status doesn't happen automatically when you form a corporation. You need to file Form 2553 — Election by a Small Business Corporation — with the IRS. The IRS must approve the election before the tax treatment takes effect.

The timing matters. To have S corp status apply for the current tax year, you generally need to file Form 2553 no later than 2 months and 15 days after the start of that tax year, or at any point during the prior tax year. Missing that window means the election takes effect the following year.

All shareholders must consent to the election by signing Form 2553. If any shareholder doesn't sign, the IRS won't approve it. That's a detail that catches some business owners off guard when they're moving quickly.