C corp vs S corp vs LLC: which one a venture-backed startup needs

In the C corp vs S corp choice, a startup raising venture money needs a C corporation. Here is why, and what converting from an LLC does to QSBS.

Vishant Mehta, CPA, Ex-Big 4

Published October 31, 2026

startups
C corp
S corp
LLC
QSBS
entity choice

A startup that plans to raise from venture funds should be a C corporation. An S corporation cannot have a fund or a nonresident alien as a shareholder, and it cannot issue preferred stock. An LLC passes its income through to its owners, and its units can never be qualified small business stock (QSBS).

If you started as an LLC, convert before you raise. The QSBS clock starts on the conversion date, and gain built up before it is not excluded from tax.

Rule	C corp	S corp	LLC
Who pays income tax	The company, at 21%	The owners	The owners
Profit paid out	Taxed again as dividends	Usually no second tax	No second tax
Who can own it	Anyone, including funds	Up to 100, no funds	Anyone
Preferred stock	Yes	No	Units, not stock
QSBS	Yes	No	No
Federal return	Form 1120	Form 1120-S	Form 1065 if 2+ owners

Should my startup be an S corp or C corp?

Choose a C corporation if you will raise from venture funds, and an S corporation only if you never will. Section 1361 of the tax code puts four limits on an S corporation's owners and stock.

No more than 100 shareholders, with members of a family counted as one.
Only individuals, estates and certain trusts and exempt organizations as shareholders, so no funds.
No shareholder who is a nonresident alien.
One class of stock, meaning identical rights to distributions and liquidation proceeds. Preferred stock with a liquidation preference breaks it.

The election ends on the day the company breaks any limit, such as when a fund buys shares. Ending it on purpose does not rescue QSBS. Shares issued while the company was an S corporation were not C corporation stock when issued, so they can never qualify.

An S corporation suits a profitable, owner-run company that pays out its profit. Owners who work in it must pay themselves a reasonable salary before taking distributions.

Why would anyone choose C corp over S corp?

Founders choose a C corporation because it can sell any class of stock to any investor, and its stock can qualify for QSBS.

Funds can invest. A venture fund is not an individual, so it can own C corporation stock but not S corporation stock.
Preferred stock. Priced rounds typically sell preferred stock. A C corporation has no federal limit on its classes of stock.
QSBS. Only stock of a domestic C corporation can be qualified small business stock. For stock acquired after July 4, 2025, up to 100% of the gain can be excluded. The cap per company is the greater of $15 million or 10 times your basis.
A flat 21% rate. Profit the company keeps is taxed once, at 21%. Dividends are taxed again, at up to 20% plus the 3.8% net investment income tax.

That second tax is the main cost of a C corporation. On $100,000 of profit paid out in full, federal tax can reach $39,802. A startup that reinvests its profit pays no dividend tax.

Why do venture funds avoid LLCs?

Funds avoid LLCs because an LLC's business income would flow through to their own investors. An LLC with two or more members is taxed as a partnership by default, so its income and losses land on its owners' returns.

That can suit founders with early losses, subject to limits. A fund set up as a partnership would pass the income on to its investors, with two results.

A tax-exempt investor, such as an endowment, counts its share of the business income as unrelated business taxable income.
A foreign investor is treated as engaged in a US trade or business.

A C corporation blocks both, since investors receive only dividends and sale proceeds. The funds' preference is market practice, not law, and these rules explain it.

Should I reincorporate from an LLC before raising?

Yes, convert to a C corporation before a priced round, and earlier is better for QSBS. When an LLC taxed as a partnership converts under state law, the IRS treats it as two steps. The LLC contributes its assets to the corporation for stock, then hands that stock to its members.

That exchange is usually tax-free under section 351. Debt above the tax basis of the assets can still create a taxable gain.

For QSBS, the new stock counts as acquired on the conversion date, so the holding period starts then. Its QSBS basis is at least the fair market value of what the LLC contributed. Gain built up before the conversion is therefore taxed when you sell, without the exclusion.

The $75 million gross assets test also counts contributed property at its fair market value. If the LLC's assets are worth more than $75 million when it converts, the corporation cannot issue QSBS.

When does the QSBS clock start?

The clock starts when you acquire a C corporation share, or on the conversion date for a converted LLC. For stock acquired after July 4, 2025, the exclusion grows with time held.

Held since the clock started	Gain excluded
Under 3 years	None
3 years	50%
4 years	75%
5 years or more	100%

So converting while the company is worth little starts the clock early and keeps more of the later gain excludable.

What should you do now?

If you plan to raise, form a C corporation before you take outside money.
If you form it in Delaware, it owes an annual report and Delaware franchise tax by March 1 each year.
If you are an LLC, convert before your priced round. Record the company's fair market value on the conversion date, since it sets your QSBS starting point.
If you are an S corporation, talk to a CPA before any fund or foreign investor buys shares.
Once you are a C corporation, file Form 1120 every year, even with no revenue.

For returns and advice from founding to exit, see our startup accountant service.