S Corporations | The Tax Status That Can Vanish Before You Close

You're buying a business organized as an S corporation. The seller has been passing income through to shareholders, paying tax at individual rates, avoiding the double taxation of a C corporation. The deal is priced accordingly — the flow-through structure is part of the value.

Then, somewhere in diligence, someone finds a problem. A shareholder who shouldn't have been a shareholder. A second class of stock that technically wasn't supposed to exist. A corporate investor that held shares for six months three years ago. Any one of those things, at any point in the company's history, could mean the S corporation election was already dead before you ever signed a letter of intent.

And if it was, you're not buying an S corporation. You're buying a C corporation with years of unpaid taxes, penalties, and interest — and a seller who may not have known, or may not be telling you.

What makes a company eligible to be an S corporation

S corporation status isn't automatic. A company has to elect it, and to keep it, it has to stay inside a set of strict eligibility boxes at all times. The rules have been in place for decades, but they're surprisingly easy to violate — often accidentally, often without anyone noticing until a deal surfaces the issue.

The core requirements: the company must be a domestic corporation, it can have no more than 100 shareholders, every shareholder has to be a US individual, a qualifying estate, or a specific type of trust — no corporations, no partnerships, no foreign persons. And there can only be one class of stock.

That last one is where deals most commonly blow up.

But first — was the election ever validly made?

Before you even get to whether the S corporation status has been maintained, there's a threshold question that diligence frequently misses: was the original election valid in the first place?

To elect S corporation status, the company files Form 2553 with the IRS — but the form alone isn't enough. Every shareholder who held stock on the date of the election must consent to it in writing. That sounds straightforward until you consider what "every shareholder" actually means in practice.

In community property states — California, Texas, Arizona, Nevada, Washington, Idaho, Louisiana, New Mexico, and Wisconsin — stock held by a married shareholder is generally treated as community property, meaning the spouse has a ownership interest in those shares even if their name appears nowhere on the cap table. If the spouse's consent wasn't obtained when the Form 2553 was filed, the election may never have been valid.

This is not a theoretical risk. Closely held businesses often elect S corporation status early, informally, and without specialized tax counsel. A founder in California files Form 2553 with their own signature. Their spouse's name is nowhere on it. The IRS may have acknowledged the election — the acknowledgment letter is not a guarantee of validity — and the company has been filing as an S corporation for ten years. None of that fixes the underlying defect.

There is a remedy: the IRS allows late or corrective elections under a streamlined procedure, and invalid elections can sometimes be ratified. But discovering this in the middle of a deal, under time pressure, creates exactly the kind of closing risk no buyer wants.

The one class of stock rule — the hidden terminator

The one class of stock rule means every share has to carry identical rights to distributions and liquidation proceeds. That sounds simple. In practice, it isn't. Shareholder loans with below-market interest rates, employment agreements that give certain shareholders preferential economic treatment, buy-sell agreements with non-standard redemption terms — any of these can be argued to create a second class of stock, even if no one ever issued a different share certificate.

The IRS has a safe harbor for straight debt, which protects certain loans from being recharacterized as a second class of stock — but the conditions are specific and frequently not met in closely held businesses that haven't been thinking about this carefully.

What termination actually means

If the S election terminates — whether because a new ineligible shareholder comes in, someone violates the one class of stock rule, or the shareholder transferred his shares to an inegibile trust without telling the S corporation’s tax preparer — the corporation converts to a C corporation on the date of the terminating event. Going forward it pays corporate tax. But the real damage in an M&A context is usually historical.

If the termination happened in a prior year, the company has been filing S corporation returns it shouldn't have been filing. The income those returns showed flowing through to shareholders should have been taxed at the corporate level. The IRS can assess that tax, plus penalties, plus interest, against the corporation — and after you close, that corporation is yours.

There is an inadvertent termination relief provision in the tax code. The IRS can restore S corporation status if the termination was genuinely accidental and the company corrects the issue promptly. But that process takes time, requires IRS cooperation, and isn't guaranteed — and it doesn't make the back-tax exposure disappear cleanly.

What buyers should be doing

Three things that should be standard in any acquisition of a company with S corporation status:

First, trace the shareholder history — not just the current cap table. Who owned shares at any point in the last three to five years? Were there any transfers, gifts, or inheritances that might have put shares in the hands of an ineligible holder, even briefly? Trust structures are a particular area to examine — not every trust qualifies as an eligible S corporation shareholder.

Second, review all shareholder agreements, loan agreements, and compensation arrangements for anything that might create differential economic rights. The question isn't whether the document says "second class of stock" — it's whether the economic effect is equivalent to one.

Third, get a representation in the purchase agreement that the S election has been continuously valid since it was made, and back it up with indemnification that survives long enough to cover any IRS assessment. A standard 12-month survival cap is not sufficient here.

In The Deep End below, we go through the eligibility requirements section by section, the mechanics of termination and the post-termination transition period, inadvertent termination relief under Section 1362(f), and the specific diligence items and representations that competent M&A tax counsel should be addressing in every S corporation acquisition.

To make and maintain a valid S election under §1361 and §1362, a corporation must satisfy all of the following requirements continuously. Failure of any single requirement on any single day terminates the election as of that date.

Domestic Corporation Requirement

The entity must be a domestic corporation — incorporated under U.S. law. Foreign corporations are categorically ineligible. Certain domestic corporations are also ineligible regardless of other factors, including insurance companies taxed under Subchapter L, domestic international sales corporations (DISCs), and corporations that have made a §936 election. In practice this requirement rarely creates diligence complexity, but confirm the state and jurisdiction of incorporation as a threshold matter.

Shareholder Limitations — Number and Identity

An S corporation may not have more than 100 shareholders. §1361(b)(1)(A). For this purpose, members of a family (defined broadly under §1361(c)(1) to include a common ancestor and all lineal descendants, plus their spouses) may elect to be treated as a single shareholder — a provision that effectively extends the 100-shareholder limit for family-owned businesses significantly beyond what it appears. In diligence, confirm whether a family election has been made, as its absence in a large family-owned business could mean the shareholder count has already exceeded 100.

Every shareholder must be one of the following:

Ineligible shareholders include: C corporations, S corporations (with narrow exceptions), partnerships, LLCs treated as partnerships, nonresident aliens, and certain foreign trusts. The presence of any ineligible shareholder for even a single day terminates the S election.

Diligence focus: Trust structures are the most frequent source of inadvertent termination in M&A targets. When shares are held in trust, confirm: (i) the type of trust, (ii) whether the required election (QSST or ESBT) was timely made and remains in effect, (iii) whether the trust has been modified or decanted in a way that could affect its eligibility, and (iv) whether the trustee or beneficiary is a nonresident alien.

One Class of Stock Requirement

Under §1361(b)(1)(D), an S corporation may have only one class of stock. Reg. §1.1361-1(l)(1) defines a single class of stock as requiring that all outstanding shares confer identical rights to distribution and liquidation proceeds. Differences in voting rights alone do not create a second class of stock — voting and nonvoting common stock can coexist in an S corporation. §1361(c)(4). Everything else must be economically identical.

Procedural Requirements for a Valid S Election

A valid S election requires timely filing of Form 2553 signed by an officer of the corporation, accompanied by the written consent of every shareholder who held stock on the date the election is made, and every shareholder who held stock during the portion of the taxable year before the election was made if the election is to be effective for that year. §1362(a)(2); Reg. §1.1362-6(a)(2). The consent requirement is not a formality — an election filed without the consent of all required shareholders is invalid, and an invalid election means the corporation has never been an S corporation regardless of how it has been filing.

The IRS issues an acknowledgment letter upon receipt of Form 2553, but that acknowledgment is administrative confirmation of receipt — it is not a legal determination that the election is valid. Practitioners and taxpayers sometimes treat the acknowledgment as conclusive; it is not.

Timing Requirements

To be effective for a taxable year, the election must be filed: (i) at any time during the preceding taxable year, or (ii) on or before the 15th day of the third month of the taxable year for which it is to be effective. §1362(b)(1). An election filed after the 15th day of the third month is treated as effective for the following taxable year — a timing defect that, if undetected, means the corporation operated as a C corporation for the year it believed it had S corporation status.

The Community Property Spouse Consent Requirement

In the nine community property states — California, Texas, Arizona, Nevada, Washington, Idaho, Louisiana, New Mexico, and Wisconsin — stock acquired during marriage is generally characterized as community property under state law, giving each spouse an undivided one-half interest in the shares regardless of how title is held. Under Reg. §1.1362-6(b)(2)(i), if a shareholder's stock is community property, or if the income from the stock is community property, both the shareholder and the shareholder's spouse must consent to the S election — even if the spouse is not a registered shareholder and does not appear on the stock ledger.

The failure to obtain spousal consent in a community property state is one of the most commonly encountered Form 2553 defects in M&A diligence. The scenario is predictable: a founder or small group of founders organizes a corporation, makes an S election early in the company's life, signs the Form 2553 themselves, and never considers whether their spouses hold a community property interest requiring separate consent. The IRS acknowledges the election. The company files S corporation returns for years. No one looks at this again until a buyer's tax counsel requests the original Form 2553 in diligence.

Diligence protocol: For every shareholder who signed Form 2553, confirm: (i) their state of domicile at the time the election was made; (ii) whether they were married at that time; and (iii) whether their spouse provided a separate consent if domiciled in a community property state. If available, obtain a copy of the original Form 2553 with all shareholder consent statements — not just the IRS acknowledgment letter.

Late Election Relief — Rev. Proc. 2013-30

The IRS provides a streamlined procedure for obtaining relief for late, invalid, or defective S elections under Rev. Proc. 2013-30. Relief is available where the failure to timely or validly elect was due to reasonable cause, and the corporation has filed returns consistent with S corporation status for all relevant years (or has not yet filed returns for those years). The procedure covers: (i) late elections, (ii) elections that were timely filed but lacked required shareholder consents, and (iii) elections that were invalid due to missing or defective spousal consents in community property states.

To obtain relief, the corporation files a completed Form 2553 with a statement explaining the reason for the failure and attaching all required consents — including retroactive spousal consents where applicable. If the failure is discovered more than 3 years and 75 days after the intended effective date, the streamlined procedure is unavailable and relief requires a private letter ruling under the general inadvertent termination provisions of §1362(f), which is more costly and uncertain.

M&A implication: Where a Form 2553 defect is identified in diligence, the availability of Rev. Proc. 2013-30 relief depends critically on timing. If the election was intended to be effective more than 3 years and 75 days before the diligence date, streamlined relief is unavailable. The buyer faces a choice between: (i) seeking a PLR under §1362(f) — expensive, slow, and uncertain; (ii) restructuring the deal to treat the target as a C corporation and repricing accordingly; or (iii) accepting the risk with appropriate indemnification. None of these is a good outcome discovered at the letter of intent stage. This is an argument for front-loading S corporation election validity as a threshold diligence question, not a confirmatory one.

Shareholder Agreements and Buy-Sell Arrangements

Under Reg. §1.1361-1(l)(2)(iii), a buy-sell agreement, redemption agreement, or similar arrangement is disregarded in determining whether shares confer identical distribution and liquidation rights — unless a principal purpose of the agreement is to circumvent the one class of stock requirement, or the agreement establishes a purchase price that, at the time it is entered into, is not reasonably related to fair market value. The "principal purpose" standard gives the IRS meaningful latitude in egregious cases; in practice, most standard buy-sell arrangements survive scrutiny, but agreements with trigger-based pricing that produces materially different economic outcomes for different shareholders warrant analysis.

Shareholder Loans and the Straight Debt Safe Harbor

An instrument characterized as equity rather than debt will be treated as a second class of stock if it confers distribution or liquidation rights different from those of the outstanding common shares. The straight debt safe harbor under §1361(c)(5) and Reg. §1.1361-1(l)(5) protects qualifying instruments from reclassification. To qualify, the instrument must: (i) be an unconditional promise to pay a sum certain on demand or on a specified date; (ii) bear interest at a rate not contingent on profits, borrower's discretion, or similar factors; (iii) not be convertible into stock; and (iv) be held by an individual, estate, or certain trusts that would be eligible shareholders.

Loans that fail the straight debt safe harbor — particularly convertible notes, profit-participating loans, or loans held by ineligible holders — are analyzed under general debt/equity principles. If recharacterized as equity with economic rights different from outstanding shares, S election termination follows.

Diligence protocol: Request and review all outstanding promissory notes, loan agreements, and advances between the corporation and its shareholders. Confirm interest rates are fixed or at an AFR-based rate, confirm no conversion features exist, and confirm holder eligibility. Review shareholder agreements for distribution provisions that deviate from strict pro-rata treatment.

Employment Agreements and Compensation Arrangements

Compensation arrangements that effectively provide one class of shareholders with superior economic returns — through above-market compensation to shareholder-employees that functions as a disguised distribution — can attract IRS scrutiny under the one class of stock rules, though this theory is less frequently litigated than the loan recharacterization theory. More practically, compensation arrangements that tie bonuses or deferred compensation to ownership percentage rather than services can create economic equivalence to a second distribution right.

Voluntary vs. Involuntary Termination

An S election may be terminated voluntarily under §1362(d)(1) by revocation consented to by shareholders holding more than 50% of outstanding shares. Involuntary termination under §1362(d)(2) and (3) occurs either (i) upon ceasing to be a small business corporation — i.e., failing any §1361 eligibility requirement — or (ii) having passive investment income exceeding 25% of gross receipts for three consecutive years while having accumulated earnings and profits from C corporation years.

Involuntary termination is effective on the date the disqualifying event occurs. For a corporation that has operated as an S corporation for years and then experiences a terminating event — an ineligible shareholder acquires shares, a trust fails to maintain its QSST election, a convertible note is issued — the S election terminates as of that date, and the corporation is treated as a C corporation from that point forward.

The Post-Termination Transition Period (PTTP)

The post-termination transition period under §1377(b) runs from the day after the last day of the corporation's last taxable year as an S corporation through the later of: (i) one year after that date, or (ii) the due date (including extensions) of the last S corporation return. During the PTTP, shareholders may receive distributions of the corporation's accumulated adjustments account (AAA) in cash, treated as coming from the AAA rather than from accumulated C corporation earnings and profits — avoiding dividend treatment. Once the PTTP expires, distributions draw from accumulated E&P and are taxed as dividends to the extent thereof.

In M&A, the PTTP is relevant where a target's S election has recently terminated — voluntarily as part of deal structuring, or inadvertently — and accumulated AAA distributions remain available. Confirming PTTP timing and AAA balance is a diligence item in any deal involving a recent S-to-C conversion.

Passive Investment Income Termination

Where a target has accumulated E&P from prior C corporation years, confirm that passive investment income has not exceeded 25% of gross receipts for three consecutive taxable years. §1362(d)(3). This termination trigger is less commonly encountered but arises in targets that converted from C corporation status without distributing accumulated E&P and subsequently derived significant passive income — interest, rents, royalties, dividends, and annuities. If the threshold has been exceeded for two consecutive years as of closing, the S election is one year away from involuntary termination regardless of buyer intent.

Under §1362(f), the IRS may waive an inadvertent termination if: (i) the IRS determines the termination was inadvertent; (ii) within a reasonable period after discovery, steps are taken to correct the event that caused termination; and (iii) the corporation and shareholders agree to adjustments consistent with S corporation treatment during the period of termination. Relief is discretionary — the IRS is not required to grant it.

Relief under §1362(f) is routinely sought and frequently granted for genuinely inadvertent terminations — a trust that failed to timely make a QSST election, a shareholder who briefly held shares through an ineligible entity before correcting the structure, a convertible note issued without recognizing its S corporation implications. The IRS has established a user fee procedure for these requests.

Critical M&A implication: the existence of a §1362(f) request — whether pending or previously granted — should be treated as a significant diligence flag. A previously granted relief request confirms a prior termination event occurred. A pending request means the S corporation status is currently uncertain. In either case, the purchase agreement representations and indemnification provisions must address the specific facts of the relief request, and the buyer should obtain copies of all IRS correspondence related to the relief proceeding.

Tax Diligence Checklist for S Corporation Acquisitions

The following items represent the core S corporation-specific diligence workstream, layered on top of standard tax diligence:

Shareholder history review: Obtain the complete shareholder history from the date of S election through the proposed closing date. Confirm all current and historical shareholders were eligible at all times. Pay particular attention to estate transfers where shares passed to trusts, gifts to minors held in custodial accounts or trusts, divorce settlements, and any period in which shares were held by a non-U.S. person.

Trust analysis: For each trust appearing in the shareholder register, confirm trust type and obtain copies of the trust agreement, any QSST or ESBT election with evidence of timely filing, beneficiary information, and any modifications to the trust since the election was made. Confirm current trustee and beneficiary residency and citizenship status.

Instrument review: Obtain and analyze all shareholder loans, convertible instruments, warrants, options, and phantom equity arrangements. Map each against the straight debt safe harbor requirements and confirm no instrument creates differential economic rights equivalent to a second class of stock.

Shareholder agreement review: Review all stockholder agreements, buy-sell agreements, and rights of first refusal for provisions that create non-pro-rata distribution rights, redemption terms linked to formula pricing, or other economic differentiators between shareholders.

Prior IRS correspondence: Request all IRS correspondence relating to the S election, including the original election acknowledgment letter, any §1362(f) relief requests or determinations, and any audit adjustments to S corporation returns.

Passive investment income analysis: If the target has any accumulated E&P from prior C corporation years, confirm passive investment income has not exceeded 25% of gross receipts for three consecutive taxable years and assess the risk for current and future years.

Purchase Agreement Protections

At minimum, the purchase agreement should contain:

A representation that the S election was validly made, has been continuously in effect since the election date, and no event has occurred that would cause or constitute a termination of the S election. This representation should be unqualified — a knowledge qualifier is insufficient given the objective nature of the eligibility rules.

An indemnification covering: (i) any federal or state tax liability arising from a termination of the S election prior to closing; (ii) any interest and penalties associated with C corporation tax obligations for periods the company filed as an S corporation; and (iii) the costs of obtaining §1362(f) relief if required post-closing.

Survival period of at minimum the applicable federal statute of limitations for each S corporation taxable year — three years from filing for standard years, six years where substantial omission is possible. The indemnification should not be subject to a general basket or cap where the potential exposure is material relative to deal size.