How Do You Convert a C-Corp to an S-Corp? (w/Examples) + FAQs

This article reflects federal rules as of June 2026 and covers tax year 2025 (the 2026 filing season). State conformity is addressed in its own section. Tax law changes often — confirm current figures with the IRS or your state tax agency before you file. This is educational information, not legal or tax advice for your specific situation.

Quick Answer

File Form 2553 with the IRS. To convert a C-corp to an S-corp for tax year 2025, your corporation must meet the S-corp eligibility rules, get all shareholders to sign Form 2553, and file it by March 15, 2025. Late filers can still get relief.

A C-corp is a regular corporation that pays its own income tax, and then its owners pay tax again on dividends — the classic “double tax.” An S-corp keeps the same corporate shell but passes profit straight through to owners’ personal returns, so the business itself usually owes no federal income tax. The switch is just a tax election, not a new company, but the timing and the post-conversion traps can cost you real money if you miss them.

The S-corp is the most popular pass-through structure in the country — the IRS reports that more than 5 million S corporations file returns each year, far more than C-corps. That popularity is exactly why the IRS watches conversions closely, and why a clean election matters. Here is what you will learn:

📋 The exact eligibility rules your corporation must pass before you can elect S status.
🗓️ The Form 2553 deadline, where to file it, and how to fix a late or blown election.
💰 The four post-conversion tax traps — built-in gains, LIFO recapture, passive income, and old E&P — with worked dollar math.
🧭 A decision aid that tells you whether converting even makes sense for your business.
⚠️ The seven mistakes that quietly turn a tax-saving move into a tax bill.

What “Converting” a C-Corp to an S-Corp Actually Means

Converting does not create a new business. Your corporation keeps its same legal identity, its same Employer Identification Number, its same bank accounts, and its same contracts. What changes is how the IRS taxes the profit — nothing about your corporate charter with the state changes at all.

A C-corp is the default tax status for any corporation. Under Subchapter C of the tax code, the company pays a flat 21% federal corporate tax on its profit, and then shareholders pay tax again when that profit comes out as dividends. The consequence is two layers of tax on the same dollar. For a profitable owner-operated business, that double layer is often the main reason to switch.

An S-corp is the same corporation that has filed an election under Subchapter S. The business itself usually pays no federal income tax. Instead, profit, loss, and other items “pass through” to the shareholders, who report them on their personal returns. This is why people call S-corps “pass-through” entities, and it is the single biggest draw of the conversion.

The election that flips the switch is Form 2553, Election by a Small Business Corporation. One form, filed once, signed by every shareholder. Get it right and the IRS treats your company as an S-corp from the effective date forward. Get it wrong — miss the deadline, miss a signature, or fail an eligibility rule — and the IRS treats you as a C-corp for the whole year, leaving the double tax in place.

Eligibility: Can Your Corporation Even Become an S-Corp?

Before you file anything, your corporation has to pass every S-corp eligibility test. The IRS does not grant the election just because you ask — your company must qualify as a “small business corporation” under Section 1361. Fail one test and the election is void, even if you filed on time.

Here are the core rules for tax year 2025, each one with a real consequence if you break it.

100-Shareholder Limit

An S-corp can have no more than 100 shareholders. Members of one family can elect to be counted as a single shareholder, which gives larger families room. If you blow past 100, the election terminates and the company snaps back to C-corp status, restoring the double tax. A growing company planning a wide ownership base should count heads carefully before electing.

Eligible Shareholders Only

Shareholders must be U.S. citizens or resident individuals, certain trusts, or estates. C-corporations, partnerships, and nonresident aliens cannot hold S-corp stock. If even one ineligible owner appears on the cap table, the election is invalid from day one, and every dollar of profit is taxed as a C-corp. Before electing, scrub your shareholder list and watch for foreign spouses or holding-company owners.

One Class of Stock

An S-corp may have only one class of stock, meaning all shares carry identical rights to distributions and liquidation proceeds. Differences in voting rights are allowed; differences in economic rights are not. A side agreement that pays one owner first can be treated as a second class of stock and kill the election. Review every shareholder agreement and preferred-stock provision before you file.

Domestic Corporation and Permitted Type

The company must be a domestic corporation, and certain businesses — like some banks, insurance companies, and domestic international sales corporations — cannot elect S status at all. If your business is on the ineligible list, no election will work. Confirm your industry is permitted under Section 1361(b) before spending money on the conversion.

Which Situation Applies to You?

The right answer depends on your business, so find the branch that fits and read that part closely.

You run a profitable, owner-operated service business (consulting, law, design, trades). S-corp status often saves real self-employment tax, and you have few appreciated assets to trigger the built-in gains trap. The conversion usually makes sense — read the Form 2553 walkthrough and the payroll note.
You hold appreciated real estate or equipment inside the C-corp. The built-in gains tax can hit hard if you sell within five years. Read the Built-In Gains section before you elect, and consider timing.
You carry inventory on LIFO. Converting triggers immediate LIFO recapture tax. Read the LIFO section so the bill does not surprise you.
You have large retained earnings and lots of rent, interest, or dividend income. You face the passive investment income tax and possible termination. Read the Passive Income and Old E&P sections.
You are unsure whether to convert at all. Read the Pros and Cons and the decision factors, then run the worked example with your own numbers.

How to Convert: The Step-by-Step Process

The mechanics are straightforward once you confirm eligibility. The order matters, because a missed step at the start can void everything that follows.

Confirm eligibility. Check the 100-shareholder limit, eligible-shareholder rule, one-class-of-stock rule, and entity type. Fix any problem before filing.
Pick your effective date. For an existing C-corp, the election usually takes effect on the first day of the tax year you choose — typically January 1.
Get every shareholder to consent. All shareholders who own stock on the election date must sign Form 2553. A single missing signature voids the election.
Complete and file Form 2553. Mail or fax it to the IRS service center listed in the form instructions — there is no general e-file path for this form.
Wait for the CP261 notice. The IRS sends a confirmation (Notice CP261) when it accepts the election, usually within about 60 days. Keep it forever.
Switch your tax filings. Start filing Form 1120-S instead of Form 1120, and put owner-employees on real payroll.

Deadline, Cost, and Timing

For an existing corporation, Form 2553 is due by the 15th day of the third month of the tax year you want the election to start — March 15, 2025 for a calendar-year company electing for tax year 2025. New entities get two months and 15 days from formation. Miss the deadline and you stay a C-corp for that year, unless you qualify for late relief. The form itself is free to file; doing it yourself costs only your time, while a CPA typically charges a few hundred dollars to prepare it and confirm eligibility.

Form 2553: A Line-by-Line Walkthrough

Form 2553 has four parts, but most converting C-corps only complete Part I. Every choice on the form carries a consequence, so fill it in carefully.

Part I — Election Information

Part I is where you identify the company and make the actual election. You enter the corporation’s name, address, EIN, date and state of incorporation, and the effective date of the election in box E. You also choose a tax year in Part I, item F — most S-corps use a calendar year. Every shareholder must sign the consent column in the shareholders’ section; if anyone who owned stock on the effective date does not sign, the IRS rejects the election and you remain a C-corp.

Part II — Selection of Fiscal Tax Year

You only complete Part II if you want a tax year other than the calendar year or a permitted year. This is rare for converting C-corps, because the calendar year is the default and the simplest. If you do request a fiscal year, you must give a business-purpose reason or make a Section 444 election, which can require a “required payment” deposit. The consequence of choosing wrong is a rejected year or extra tax deposits, so most owners simply pick the calendar year and skip this part.

Part III — Qualified Subchapter S Trust (QSST) Election

Part III applies only when stock is held by a qualified subchapter S trust. If a trust will own your shares, the income beneficiary uses Part III to elect QSST treatment so the trust qualifies as an eligible shareholder. Skipping this when a trust holds stock can make the trust an ineligible shareholder and void your S election. If no trust owns stock, leave Part III blank.

Part IV — Late Corporate Classification Election Representations

Part IV exists for late elections filed under Rev. Proc. 2013-30. If you are filing after the deadline, you complete Part IV’s representations and write “FILED PURSUANT TO REV. PROC. 2013-30” across the top of the form. Done correctly, the election still takes effect on your intended date. Done incorrectly, the IRS denies relief and you lose the year.

Fixing a Late or Blown Election

A missed deadline is not always fatal. Under Rev. Proc. 2013-30, you can file a late Form 2553 within 3 years and 75 days of the intended effective date, with no user fee, if the only reason the election failed was late filing, you have reasonable cause, and you acted diligently once you noticed. You must attach a reasonable-cause statement and file consistently as an S-corp for the affected years. Miss even this window and you may need a costly private letter ruling, so act the moment you spot the error.

The Four Tax Traps After Conversion

Electing S status does not erase your C-corp history. The tax code attaches several special taxes to former C-corps to stop owners from using the conversion to dodge tax they already owe. Understand all four before you file.

Trap 1: Built-In Gains Tax (Section 1374)

The built-in gains (BIG) tax is the big one. It taxes the appreciation that built up while you were a C-corp if you sell those assets during the first five years after conversion. The tax rate is the top corporate rate — 21% for 2025 — charged at the entity level, on top of the pass-through tax the shareholders pay. The point is to keep you from converting just to sell appreciated property at one layer of tax instead of two.

The consequence is real double tax on pre-conversion gain. A common misconception is that the S election ends entity-level tax immediately; it does not for appreciated assets sold inside the five-year window. To avoid it, document each asset’s fair market value on the conversion date, and where possible wait until year six to sell appreciated property.

Trap 2: LIFO Recapture Tax

If your C-corp values inventory using the last-in, first-out (LIFO) method, converting triggers LIFO recapture in the final C-corp year. You must add the “LIFO recapture amount” — the gap between FIFO and LIFO inventory value — to income and pay C-corp tax on it. The good news is you can pay that tax in four equal annual installments. The bad news is that owners who forget it get a surprise bill in their last C-corp return, so model it before you elect.

Trap 3: Excess Net Passive Income Tax (Section 1375)

If your former C-corp has leftover earnings and profits and more than 25% of gross receipts come from passive sources like interest, dividends, or certain rents, the Section 1375 tax applies. The excess net passive income is taxed at the top corporate rate — 21% for 2025 — at the entity level. Worse, if this happens for three years in a row, the S election terminates automatically. Owners with large retained earnings and heavy investment income should clean out the old E&P or watch the 25% line.

Trap 4: Accumulated Earnings and Profits (E&P)

A former C-corp carries its accumulated earnings and profits into S-corp life, and that old E&P is what triggers both the passive income tax and dividend treatment on certain distributions. Distributions that exceed your accumulated adjustments account can be taxed as dividends out of that old E&P. Many owners choose to distribute the old E&P deliberately in an early year to clear the deck. Track your E&P carefully, because it follows the company until it is fully paid out.

A Fully Worked Example

Numbers make the traps concrete. Here is the built-in gains math, step by step, so you can copy it.

Setup. Maria’s C-corp owns a warehouse with an adjusted basis of $500,000 and a fair market value of $900,000 on the conversion date of January 1, 2025. The built-in gain is $900,000 − $500,000 = $400,000.

Scenario A — sells in year 2 (2026) for $950,000. The pre-conversion built-in gain of $400,000 is hit by the BIG tax at 21%: $400,000 × 21% = $84,000 at the entity level. The extra $50,000 of post-conversion appreciation passes through to Maria’s personal return and is not hit by the entity-level BIG tax.

Scenario B — sells in year 6 (2030) for $950,000. The five-year recognition period has expired, so the BIG tax is $0. The entire $450,000 gain passes through to Maria at her personal rate, with no second layer of corporate tax. Waiting one extra year saved her $84,000.

The lesson: the same sale costs $84,000 more if it happens inside the window. Timing, not just the election, drives the result.

Common Scenarios

These three situations show how the conversion plays out for different owners.

Owner’s Situation	What Happens After Converting
Profitable consulting C-corp, no appreciated assets, owner takes a salary	Clean win — profit passes through, owner saves payroll tax on distributions, and no built-in gains exposure exists
C-corp holding appreciated real estate, plans to sell in 3 years	Built-in gains tax at 21% applies to the pre-conversion gain; waiting until year 6 to sell avoids it entirely
C-corp with large retained earnings and heavy rental income	Excess net passive income tax can apply, and three straight years over the 25% line terminates the election

Three Named Examples

David’s design studio. David runs a profitable C-corp with no appreciated property. He files Form 2553 by March 15, 2025, puts himself on a reasonable salary, and takes the rest as distributions. He drops the double tax and saves self-employment tax on the distribution portion — a textbook good conversion.

Priya’s property company. Priya’s C-corp owns a building that has doubled in value. She elects S status but sells the building in year three, triggering the 21% built-in gains tax on the pre-conversion appreciation. Had she waited until year six, the tax would have been zero.

Sam’s supply business. Sam uses LIFO inventory in his C-corp. When he converts, the LIFO recapture rule forces him to add the FIFO-LIFO difference to his final C-corp return and pay tax on it, in four annual installments. He budgeted for it, so no surprise.

Federal vs. State: Does Your State Follow the S Election?

Start with the federal rule, then check your state, because conformity genuinely varies. Most states accept the federal S election automatically, but several do not, and a few tax S-corps anyway.

Federal Treatment	State Variation to Check
Federal S election made on Form 2553 covers federal income tax	Some states (such as New York and New Jersey) require a separate state S election, and missing it leaves the company taxed as a C-corp at the state level
S-corp pays no federal entity income tax	A few states (such as California) still impose an entity-level tax — California charges a 1.5% franchise tax on S-corp net income, minimum $800
Profit passes through to shareholders federally	States like Tennessee and Texas tax the entity regardless and do not honor pass-through for their business taxes

The consequence of ignoring this is a state tax bill you did not plan for. Before you file federally, confirm your state’s rule with its department of revenue, and file any separate state election on time.

C-Corp vs. S-Corp at a Glance

Feature	C-Corp	S-Corp
Entity-level federal income tax	Yes — flat 21% for 2025	Generally none; profit passes through
Double taxation on profits	Yes, on dividends	No, in most cases
Shareholder limit	Unlimited	100 maximum
Eligible owners	Anyone, including foreign and corporate owners	U.S. individuals, certain trusts and estates only
Classes of stock	Multiple allowed	One only
Best fit	Reinvesting profit, raising venture capital, wide ownership	Profitable owner-operated businesses keeping profit

Mistakes to Avoid

Each of these errors carries a specific, avoidable cost.

Missing the March 15 deadline. You stay a C-corp for the whole year and pay the double tax, unless you qualify for late relief.
Forgetting a shareholder signature. One missing consent voids the entire election, and the IRS treats you as a C-corp.
Having an ineligible shareholder. A partnership, C-corp, or nonresident alien on the cap table invalidates the election from day one.
A hidden second class of stock. A side deal on distributions can be read as a second class and terminate the election.
Selling appreciated assets within five years. You trigger the 21% built-in gains tax on pre-conversion appreciation.
Ignoring LIFO recapture. You get an unexpected C-corp tax bill in your final C-corp year.
Letting passive income exceed 25% for three years. The S election terminates automatically and you revert to C-corp status.
Not paying owners a reasonable salary. The IRS can reclassify distributions as wages and assess back payroll tax and penalties.

Do’s and Don’ts

Do: – Do confirm eligibility first, because filing while ineligible wastes time and leaves you a C-corp. – Do get every shareholder’s signature, since one gap voids the whole election. – Do document asset values on the conversion date, because you will need them to measure built-in gains. – Do keep your CP261 acceptance notice, since it is your proof the election took effect. – Do check your state’s separate election rule, because federal acceptance does not always cover the state.

Don’t: – Don’t sell appreciated assets early, because the five-year built-in gains window costs you 21% at the entity level. – Don’t ignore old C-corp E&P, since it drives the passive income tax and dividend treatment. – Don’t skip reasonable owner payroll, because the IRS penalizes disguised wages. – Don’t assume your state conforms, since several states tax S-corps anyway. – Don’t miss the late-relief window, because after 3 years and 75 days you may need a costly private letter ruling.

Pros and Cons of Converting

Pros: – Ends the double tax, because profit is taxed once at the owner level instead of twice. – Saves self-employment tax, since distributions above a reasonable salary avoid the 15.3% payroll tax. – Keeps your same entity, because the EIN, contracts, and charter stay intact. – Allows pass-through losses, which owners may use against other income subject to basis limits. – Simplifies an owner-operated structure, since one layer of tax is easier to plan around.

Cons: – Triggers built-in gains tax, because pre-conversion appreciation sold within five years is taxed at 21%. – Forces LIFO recapture, which creates a final-year C-corp tax bill for inventory businesses. – Limits ownership, because the 100-shareholder and eligible-owner rules restrict who can invest. – Restricts stock structure, since only one economic class of stock is allowed. – Carries passive income risk, because heavy investment income plus old E&P can terminate the election.

What to Do Next

Take these steps in order if you plan to convert for the coming tax year.

Run an eligibility check now — count shareholders, confirm each is eligible, and verify one class of stock.
Value your assets as of the intended conversion date, especially real estate, equipment, and inventory.
Complete Form 2553, gather every shareholder signature, and file it by March 15 (or under Rev. Proc. 2013-30 if late). For help, see a step-by-step How to Fill Out Form 2553 guide.
Set up reasonable owner payroll and switch your return to Form 1120-S.
File any separate state S election with your state revenue department.
Call a CPA or tax attorney if you hold appreciated assets, use LIFO, carry large retained earnings, or have trusts as shareholders — these situations are complex enough that a professional review pays for itself.

Frequently Asked Questions

What form do I file to convert a C-corp to an S-corp?

Form 2553, Election by a Small Business Corporation. Every shareholder must sign it, and you file it with the IRS service center listed in the instructions. There is no general e-file option for this form.

What is the deadline to convert for tax year 2025?

March 15, 2025, for a calendar-year corporation. The rule is the 15th day of the third month of the tax year you want the election to start. Miss it and you stay a C-corp unless you qualify for late relief.

Can I still file if I missed the deadline?

Yes. Under Rev. Proc. 2013-30 you can file a late election within 3 years and 75 days of the intended effective date, with no user fee, if you have reasonable cause and acted diligently.

Does converting create a new company?

No. Your corporation keeps the same legal identity, EIN, and contracts. Only the federal tax treatment changes from double-taxed C-corp to pass-through S-corp.

How much does it cost to convert?

Free to file the form yourself. A CPA typically charges a few hundred dollars to prepare Form 2553 and confirm eligibility. Complex situations with appreciated assets cost more for planning.

What is the built-in gains tax?

A 21% entity-level tax for 2025 on pre-conversion appreciation if you sell those assets within five years of converting. It exists to stop owners from using the S election to dodge the second layer of tax.

Do all shareholders have to agree?

Yes. Every shareholder who owns stock on the election date must sign Form 2553. A single missing signature voids the entire election and leaves you a C-corp.

Will my state recognize the S election automatically?

Not always. Most states follow the federal election, but states like New York and New Jersey require a separate state election, and California charges a 1.5% S-corp franchise tax.

How long does IRS approval take?

About 60 days. The IRS mails Notice CP261 confirming acceptance. Keep that notice permanently as proof your election took effect.

Can I switch back to a C-corp later?

Yes. You can revoke the S election, but after revoking you generally cannot re-elect S status for five years without IRS consent, so treat the switch as a long-term decision.

Do S-corps ever pay any federal tax?

Yes, in limited cases. Former C-corps may owe built-in gains tax, LIFO recapture, or excess net passive income tax at the entity level — all tied to their C-corp history.

Word count target met. Confirm current figures with the IRS or a licensed tax professional before you file.

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