One of the most critical decisions when forming or restructuring a business in the United States is choosing the right corporate structure. Under U.S. tax law (the Internal Revenue Code), every corporation defaults to being taxed as a C Corporation (C Corp) when it’s formed. However, business owners who meet certain requirements can elect to have their company taxed as an S Corporation (S Corp) instead, by filing IRS Form 2553.
This choice directly determines how much tax your company pays, how you can take profits out of the business, and even how easily you can raise money from investors. In this article, we break down the core tax differences between C Corporations and S Corporations — including double taxation, the treatment of business losses, and restrictions on fringe benefits.
Taxation Model: Double Taxation vs. Pass-Through Taxation
The most significant and widely discussed difference between a C Corp and an S Corp is how company profits are taxed.
C Corporation: Double Taxation
A C Corporation is a separate taxable legal entity, fully independent of its owners. A C Corp must pay its own corporate income tax on the net profit it earns from its business activities. Following the 2017 Tax Cuts and Jobs Act (TCJA), the top corporate tax rate for C Corporations — once as high as 35% — was reduced to a flat 21%.
After tax is paid, any profit remaining in the company is taxed a second time when distributed to shareholders as dividends, since shareholders must report that dividend income on their personal tax returns. This taxation of earnings at both the corporate level and the shareholder level is what’s known as “double taxation” — widely considered the biggest drawback of the C Corp structure.
S Corporation: Pass-Through Taxation
The biggest appeal of the S Corporation structure is that it eliminates double taxation entirely. An S Corp doesn’t pay federal income tax at the corporate level. Instead, all of the company’s profit, loss, deductions, and credits “pass through” the entity directly to its shareholders.
An S Corp reports its annual activity to the government on Form 1120-S and issues each shareholder a Schedule K-1, showing their share of the profit. Shareholders then report that income on their individual tax returns (Form 1040) and pay tax on it only once, at their personal income tax rate.
Using Business Losses
Small businesses and new ventures often operate at a loss in their first few years. How those losses can be used on a tax return depends entirely on the structure you’ve chosen.
C Corporation Losses
A C Corporation’s net operating losses (NOLs) stay locked inside the company and can’t be passed through to shareholders’ personal tax returns. Shareholders can’t use these losses to offset other personal income, such as W-2 wages. Instead, the C Corp carries its own losses forward to reduce corporate tax in future profitable years. (If the C Corp’s stock was issued under Section 1244, shareholders may be able to claim a special loss deduction if the company later fails.)
S Corporation Losses
In an S Corporation, business losses pass directly to shareholders via Schedule K-1. If a shareholder actively participates in the business, they can generally use that loss to offset other personal income — such as a spouse’s salary or investment income — significantly reducing their overall tax bill. However, a shareholder can only deduct losses up to the amount of their “stock basis” and “debt basis” in the S Corp. Losses exceeding that basis are suspended until basis is restored.
Ownership and Stock Restrictions
Because of its tax advantages, the IRS imposes strict ownership rules on companies that want S Corp status. C Corporations, by contrast, face no such restrictions when it comes to raising capital.
S Corporation Restrictions
- 100-shareholder limit. An S Corp can have no more than 100 shareholders.
- No foreign shareholders. All shareholders must be U.S. citizens or resident aliens. Nonresident aliens cannot own S Corp stock.
- No entity shareholders. Other C Corporations, partnerships, or most trusts cannot be shareholders. Only individuals, certain qualifying trusts (such as grantor trusts, ESBTs, or QSSTs), and estates are eligible.
- Single class of stock. S Corps may only have one class of stock (for example, common stock with no preferences). Voting rights can differ, but all shares must carry equal rights to profit distributions and liquidation proceeds.
C Corporation Freedoms
C Corporations face no limit on the number of shareholders. Foreign investors, large corporations, and venture capital funds can all freely hold C Corp stock. Companies can also issue multiple classes of stock, including preferred stock that gives investors priority rights. This flexibility is exactly why C Corps are essentially the only viable option for companies planning to raise venture capital or eventually go public.
Fringe Benefits and the “2% Shareholder” Rule
Employee benefits like health insurance, group life insurance, and meals are an important part of tax planning — and the two structures treat them very differently.
C Corps Offer Rich Fringe Benefits
C Corporations are the most tax-advantaged structure when it comes to deducting fringe benefits for shareholder-employees. Because shareholders are treated as regular employees on payroll, they can fully benefit from the company’s medical reimbursement plans, life insurance, and other tax-free benefits, just like any other employee.
The S Corp “2% Shareholder” Trap
S Corporations work very differently. Under IRS rules (§1372), shareholder-employees who own more than 2% of an S Corp’s stock are treated similarly to partners in a partnership when it comes to fringe benefits. Health and accident insurance premiums, up to $50,000 of group life insurance, and employer-provided meals can’t be excluded from these shareholders’ taxable income. Premiums the company pays for their health insurance must be added to the shareholder’s W-2 wages and are subject to income tax. (The shareholder may, however, be able to deduct that premium on their personal Form 1040 as a self-employed health insurance deduction.)
FICA Tax Savings vs. the Accumulated Earnings Tax
The two structures also differ sharply in how owners take money out of the business — and how that money gets taxed.
S Corporation: “Reasonable Salary” Plus Distributions
S Corp owners who actively work in the business are required to pay themselves a “reasonable salary” through payroll. That salary is subject to a 15.3% FICA tax (Social Security and Medicare). However, any remaining profit paid out as a shareholder “distribution” — after a reasonable salary has been paid — is not subject to FICA tax. This strategy can save high-earning S Corp owners tens of thousands of dollars in Social Security and Medicare taxes. That said, if a shareholder tries to avoid FICA tax entirely by skipping a salary and taking everything as distributions, the IRS can recharacterize those distributions as wages and impose significant penalties.
C Corporation: The Accumulated Earnings Tax
A C Corporation can choose to avoid double taxation by retaining its profits in the business rather than distributing them as dividends. These earnings, already taxed at the flat 21% corporate rate, can be kept in the company to fund growth. However, the IRS penalizes C Corps that accumulate unreasonably high earnings simply to avoid dividend taxes. For accumulated earnings beyond what’s considered a legitimate business need — generally above $250,000 — the company may owe a 20% Accumulated Earnings Tax. S Corps, which distribute profits automatically, don’t carry this risk.
The Hidden Taxes of Converting from C Corp to S Corp
Many C Corporations eventually want to convert to S Corp status to escape double taxation. But the IRS has built in several special taxes to prevent this conversion from being used as a tax-free shortcut:
- Built-in Gains (BIG) Tax. If assets that appreciated in value while the company was a C Corp (such as real estate) are sold within the first 5 years after converting to S Corp status (the “recognition period”), the company owes a 21% BIG tax on that built-in appreciation.
- LIFO Recapture Tax. If the C Corp used the LIFO (Last In, First Out) inventory method, converting to S Corp status triggers a LIFO recapture tax.
- Excess Net Passive Income Tax. If the company still holds accumulated earnings and profits (AE&P) from its C Corp years, and more than 25% of its income as an S Corp comes from passive sources (interest, rent, royalties, etc.), the company faces an additional penalty tax at the top corporate rate. Exceeding that threshold for three consecutive years automatically terminates S Corp status.
Conclusion
Whether your business should operate as a C Corporation or an S Corporation depends entirely on your current profitability, growth goals, and plans for raising investment.
If you’re running what’s essentially a “lifestyle business,” want to take profits out for yourself, and want to be able to deduct early-year business losses against your personal income, the S Corporation structure (or an LLC electing S Corp tax treatment) is generally the better fit — and benefits like the 20% Qualified Business Income Deduction (QBID) can further reduce the tax burden for S Corp shareholders.
On the other hand, if you’re planning to raise venture capital or angel investment, intend to retain profits inside the company to fund growth rather than distribute them, and want access to rich, tax-free fringe benefits, forming a C Corporation with its flat 21% corporate rate is likely to be far more advantageous in the long run.
As Samet Oynamış, an IRS Enrolled Agent and founder of Delaware Agency, often notes, choosing the wrong structure — or mistiming a conversion between the two, such as triggering BIG tax when switching from C Corp to S Corp — can create tens of thousands of dollars in unexpected tax liability.
Not sure which structure is right for your business? The team at Delaware Agency, led by IRS Enrolled Agent Samet Oynamış, offers free consultations to help you determine the right structure for your specific situation. Schedule your free consultation here.