Most California business owners think incorporating as a C corporation is the “serious” move, the grown-up structure that signals success. Then the tax bill arrives and reality lands hard: profits get taxed once at the corporate level, then taxed again the moment those profits reach the owner’s pocket. That is double taxation, and for a profitable small business it can quietly cost tens of thousands of dollars a year. The fix is often a c-corp to s-corp conversion, a single election that changes how the IRS treats your company’s income without forcing you to shut down, restructure, or start over.

This information is current as of 9/29/2026. Tax laws change frequently. Verify updates with the IRS or FTB if reading this later.

Quick Answer: What a C-Corp to S-Corp Conversion Actually Does

A c-corp to s-corp conversion changes your company’s federal tax classification from a C corporation (which pays its own tax and then passes taxed profits to shareholders) to an S corporation (which passes income straight through to shareholders’ personal returns, taxed only once). You do it by filing IRS Form 2553. In plain English: you keep the same legal entity, the same corporate shell, the same EIN, but you stop paying two layers of tax on the same dollar. For a profitable California business, this can save $10,000 to $40,000 or more per year.

Why Double Taxation Hurts C-Corp Owners the Most

Here is the trap most owners walk into. A C corporation is a separate taxpayer. It files its own return (Form 1120) and pays the flat 21% federal corporate tax on profits. That is layer one. When the corporation distributes those profits to you as a dividend, you pay tax again on your personal return, at qualified dividend rates that can reach 20% federally plus the 3.8% net investment income tax. That is layer two. California piles on its own 8.84% corporate franchise tax at the entity level too.

Run the math on a modest example. Say your C corp earns $200,000 in profit. Federal corporate tax at 21% takes $42,000. California takes another $17,680 at 8.84%. Now roughly $140,000 is left. Distribute that as a dividend and you pay personal tax again, easily another $28,000 to $33,000 depending on your bracket. You started with $200,000 and kept a little over $107,000. That is a combined effective rate north of 46% on money your own business earned.

An S corporation eliminates the corporate-level federal tax entirely. The $200,000 flows to your personal return once. You still pay California’s 1.5% S corp franchise tax, but that is a fraction of the 8.84% corporate rate. The double hit disappears. This is exactly why so many profitable business owners revisit their entity choice once profits climb past the six-figure mark.

Key Takeaway: The higher your profit, the more double taxation costs you. Once a C corp consistently clears $100,000 in profit, the conversion usually pays for itself in the first year.

How the C-Corp to S-Corp Conversion Works Step by Step

The conversion is an election, not a dissolution. You are not closing the C corp and opening a new company. You are telling the IRS to tax your existing corporation differently. Here is the actual process.

Step-by-Step: How to File Form 2553

1. Confirm you qualify. Your corporation must be domestic, have no more than 100 shareholders, have only allowed shareholders (individuals, certain trusts, and estates, but no partnerships, corporations, or non-resident aliens), and have only one class of stock.
2. Get shareholder consent. Every single shareholder must sign the election. One holdout and the election fails. This is non-negotiable under the tax code.
3. Download the current Form 2553. Use the version from IRS.gov, since older versions get rejected.
4. Complete the identifying section. Enter the corporation’s exact legal name, EIN, address, and date of incorporation, matching your Articles of Incorporation precisely.
5. Choose your effective date. To convert for the current tax year, file within 2 months and 15 days of the start of that tax year. Miss it and the election generally applies to the following year, unless you qualify for late election relief under Rev. Proc. 2013-30.
6. Collect all shareholder signatures in Part I. Each shareholder lists their shares, ownership dates, and Social Security number.
7. Submit to the correct IRS service center. The mailing address depends on your state; California filers have a designated center listed in the Form 2553 instructions.

Expect the IRS to confirm your election with a CP261 notice within about 60 days. Keep that notice permanently. It is your proof of S corp status.

California’s Extra Step: Form 100S and the FTB

Federal approval is only half the job in California. The Franchise Tax Board recognizes the federal S election automatically, but your corporation now files Form 100S instead of Form 100, and it owes the 1.5% state franchise tax on net income (with an $800 minimum). Do not forget the estimated tax payments during the year. Skipping them triggers penalties that erode the savings you worked to capture.

KDA Case Study: Manufacturing C-Corp Owner Escapes Double Taxation

Consider Raymond, who ran a specialty parts manufacturing company in the Central Valley organized as a C corporation. His business had grown steadily and was throwing off roughly $340,000 in annual profit. Because he had incorporated as a C corp years earlier on a friend’s advice and never revisited it, he was paying 21% federal corporate tax, 8.84% California corporate tax, and then personal tax again every time he pulled money out through dividends. His combined effective tax rate on distributed profit was crushing him, around $148,000 in total tax across both layers.

When Raymond came to KDA, we ran a full entity analysis. We confirmed he met every S corp eligibility test: a single class of stock, only individual shareholders, all U.S. residents, well under 100 owners. We filed Form 2553 to elect S corporation status and transitioned his California filing to Form 100S. We also restructured his compensation so he took a reasonable salary of $120,000 with the remaining profit flowing through as a distribution not subject to self-employment tax.

The result: Raymond’s federal corporate tax vanished, and the double layer on his distributions disappeared. His total first-year tax dropped by roughly $52,000. He paid KDA $6,500 for the conversion, restructuring, and first-year filings. That is a first-year return of about 8x on his investment, and the savings recur every year going forward.

Ready to see how we can help you? Explore more success stories on our case studies page to discover proven strategies that have saved our clients thousands in taxes.

The Reasonable Salary Trap Most Owners Miss

Here is where a c-corp to s-corp conversion goes wrong for the unprepared. After converting, you become both an owner and an employee. The IRS requires S corp owner-employees to pay themselves a “reasonable salary” before taking tax-advantaged distributions. Pay yourself too little to dodge payroll taxes, and you are inviting an audit.

The strategy works because salary is subject to payroll taxes (Social Security and Medicare) but distributions are not. So owners are tempted to slash salary to zero and take everything as distribution. The IRS knows this game. In examinations, they reclassify unreasonably low salaries as wages, then hit you with back payroll taxes plus penalties and interest.

What counts as reasonable? The IRS weighs your role, your experience, what comparable positions pay in your industry and region, and how much time you devote to the business. A software developer running a profitable S corp cannot credibly claim a $25,000 salary while pulling $250,000 in distributions. Getting this split right is precisely where professional tax planning services earn their keep, because the difference between an aggressive-but-defensible split and a reckless one is thousands in avoided penalties.

Red Flag Alert: An S corp owner reporting large distributions with little or no W-2 wages is one of the most common audit triggers the IRS looks for. Document your salary decision with market comparables and keep the records.

Do I Have to Worry About Built-In Gains Tax?

Yes, and this is the trap that ambushes owners who convert a C corp that owns appreciated assets. When you convert, any assets that gained value while the company was a C corp carry a hidden liability called the built-in gains (BIG) tax. If the S corp sells those appreciated assets within five years of conversion, the corporation pays a 21% tax on that built-in gain, on top of the shareholder-level tax.

In plain English: if your C corp owns real estate, equipment, or inventory that appreciated significantly, selling it too soon after converting can trigger a nasty surprise tax. The clock runs five years. This does not mean you should avoid converting. It means you should time the sale of appreciated assets carefully, ideally holding past the five-year recognition period, or planning the conversion around your asset disposition timeline.

For most service businesses without heavily appreciated assets, the BIG tax is a non-issue. But for asset-heavy companies, it deserves a dedicated conversation before you file Form 2553.

What Happens to Accumulated Earnings and Profits?

A C corporation that has been retaining profits builds up “earnings and profits” (E&P). When you convert to an S corp, that C corp E&P does not vanish. It sits on the books, and if your S corp later distributes it, that distribution can be taxed as a dividend. There are also passive income rules: if an S corp with C corp E&P earns too much passive investment income (over 25% of gross receipts) for three consecutive years, the S election can actually terminate.

The practical fix is planning your distributions to manage the E&P over time, and monitoring passive income if your company holds investments. This is niche territory, but for former C corps with large retained earnings, it is essential to get right. A clean conversion strategy accounts for E&P from day one rather than discovering the problem years later.

S Corp vs C Corp: A Side-by-Side Comparison

The table makes the tradeoff clear. C corps offer flexibility in ownership and stock structure, which matters for venture-backed startups planning to raise institutional capital. But for the vast majority of profitable, closely held California businesses, the S corp’s single layer of tax wins by a wide margin.

Should You Convert? A Decision Framework

Convert to an S corp if:

• Your business consistently profits more than $75,000 to $100,000 annually
• You are pulling money out of the company rather than reinvesting all of it
• You have 100 or fewer shareholders, all individuals and U.S. residents
• You have a single class of stock
• You want to reduce self-employment and double taxation exposure

Stay a C corp if:

• You plan to raise venture capital or issue multiple stock classes
• You have foreign or entity shareholders
• You reinvest all profits and take no distributions
• You have significant appreciated assets you plan to sell within five years

Common Mistakes That Undermine the Conversion

The conversion is straightforward on paper, but small errors cause big problems. Filing Form 2553 late without qualifying for relief pushes your effective date back a full year, meaning another year of double taxation. Forgetting a single shareholder signature voids the election. Setting an unreasonably low salary invites reclassification. Ignoring California’s Form 100S and estimated payments generates penalties. And overlooking built-in gains on appreciated assets can trigger a 21% surprise tax.

Each of these is avoidable with a checklist and professional oversight. The savings from converting are real and recurring, but only if the election holds up and the structure is defensible. If you are running a profitable corporation and want a clear read on your corporate tax position, a proper analysis pays for itself.

Frequently Asked Questions

How long does a c-corp to s-corp conversion take?

Filing Form 2553 takes an afternoon once you have shareholder consent. IRS confirmation via CP261 notice arrives in roughly 60 days. The effective date depends on when you file relative to your tax year start.

Do I get a new EIN when I convert?

No. You keep the same EIN because it is the same legal entity. Only the tax classification changes.

Can I convert back to a C corp later?

Yes, but once you revoke an S election you generally cannot re-elect S status for five years without IRS consent. Do not treat the election as something to flip back and forth.

Will converting save me money if I reinvest all profits?

Less so. The biggest savings come from eliminating double taxation on distributions. If you never distribute and reinvest everything, the C corp’s 21% rate may actually be competitive in some scenarios.

Book Your C-Corp to S-Corp Conversion Analysis

If your C corporation is throwing off six figures in profit and you are paying tax twice on the same dollar, you are almost certainly leaving thousands on the table every year. Our team will run the numbers, confirm your eligibility, handle Form 2553 and California’s Form 100S, and structure a reasonable salary that holds up under scrutiny. Click here to book your consultation now.