QSBS for Startup Founders: C-Corp Timing, the 83(b) Election, and the $15M Exclusion

IRC §1202 is the most powerful tax provision most founders never use correctly. A clean QSBS position on a $10M gain eliminates roughly $2.4M in federal tax — and post-OBBBA, the exclusion cap rose to $15M. But qualification is decided by facts that go back to the day your company was incorporated. For founders specifically, three issues kill eligibility more often than any other: entity type at issuance, the 83(b) election, and the redemption trap. Here is what you need to know, specific enough to have a real conversation with a tax advisor before your deal closes.

1. The C-Corp Requirement — and the LLC/S-Corp Conversion Trap

The most foundational requirement of §1202 is that the issuing corporation must be a domestic C-corporation at the time the stock is issued to you. Not "eventually becomes" a C-corp — at the moment of issuance.¹

Most early-stage startups begin as LLCs or elect S-corp status. If your company started as an LLC and later converted to a C-corp, the membership interests you held before conversion do not qualify as QSBS — even if the same economic interests continue in the restructured company. New C-corp shares issued at or after conversion start a fresh QSBS clock. Interests received before the conversion date do not qualify, regardless of how long the company has been operating.

A concrete scenario: A founder starts an LLC in 2020, converts to a Delaware C-corp in 2022, and receives new C-corp shares at conversion. A 2027 acquisition — 7 years after founding — gives those shares only a 5-year QSBS hold (from the 2022 conversion). That barely clears the threshold. Any shares received before 2022 under the old LLC structure: zero QSBS eligibility, regardless of hold period.

What to check: Review your cap table documentation — specifically the board resolutions, subscription agreements, and stock certificates for each grant. The date of original C-corp issuance on each tranche is what counts for the holding-period clock.

2. The 83(b) Election: Filing Within 30 Days or Watching Your Clock Slip

For founders who receive restricted stock (shares subject to vesting), the 83(b) election directly determines when your QSBS holding period begins — and missing it can cost years of eligibility.²

Without an 83(b) election

Restricted stock subject to a vesting schedule is treated as a separate property transfer for each vesting event under §83. The holding period for QSBS purposes starts on the date each tranche vests — not the grant date. In a standard 4-year vesting schedule, your last shares don't vest until month 48. The QSBS clock on those shares starts at month 48. If the company sells at month 60, those late-vesting shares have only a 12-month hold — nowhere near the 5 years required for a full exclusion.

With an 83(b) election filed within 30 days of grant

You elect to treat the entire stock grant as a taxable property transfer at the grant date, at the then-current fair market value. For founders receiving stock at or near par value ($0.0001/share), the taxable income is essentially zero. But the QSBS clock for every share starts on the grant date.²

Example: A founder receives 2,000,000 shares on January 15, 2026, with a 4-year vesting schedule. She files an 83(b) election by February 14, 2026. Her QSBS holding period for all 2,000,000 shares starts January 15, 2026 — and she hits the 5-year threshold on January 15, 2031. Without the election, her last vesting tranche doesn't start its QSBS clock until January 15, 2030, and doesn't qualify for a full exclusion until January 15, 2035.

3. Options Are Different — the Clock Starts at Exercise

If you hold incentive stock options (ISOs) or nonqualified stock options (NSOs), the QSBS analysis shifts. You don't hold shares until you exercise, and the holding period doesn't start at grant.¹

• ISOs and NSOs: The QSBS holding period starts on the exercise date — the date you pay the exercise price and receive the shares. The grant date is irrelevant for the QSBS clock.
• Early exercise: Some option plans allow early exercise before vesting. If you early-exercise and file an 83(b) election within 30 days of that early exercise, your QSBS clock starts at the exercise date even though vesting hasn't completed. This is a deliberate tax strategy: it starts the long-term capital-gain clock and the QSBS clock earlier, often at very low exercise prices when the company is young and the gross-asset test is easily met.
• The gross-asset ceiling applies at exercise, not grant: When you exercise options, that is the moment of "original issuance" for QSBS purposes. The company's gross assets must be ≤$75M at that time (for stock acquired after July 4, 2025; $50M for stock acquired on or before that date). An employee who was granted options early but exercised in a later round — when the company had already grown large — may find the gross-asset test fails at exercise, even though the grant was small-company era. This is the late-exercise trap for long-tenured employees at fast-growing companies.

4. Nominal Basis and the $15M Cap Math

Founders typically receive stock for minimal consideration — $0.0001 per share is standard for Delaware C-corps. This has a specific effect on the QSBS exclusion calculation.

The §1202 cap is the greater of $15 million or 10× your adjusted basis, per issuer per taxpayer (post-OBBBA; $10M or 10× for pre-OBBBA stock).³ For most founders:

For founders who paid par value, the flat $15M cap governs by a wide margin. The post-OBBBA increase from $10M to $15M is worth approximately $1.2M in additional tax savings per taxpayer, per issuer — a significant improvement. But in a $50M+ exit where a founder holds a large percentage, a $15M cap still means substantial taxable gain above the threshold. QSBS stacking — using non-grantor trusts and spousal gifts to multiply the per-taxpayer cap — becomes the lever for those situations. See QSBS Stacking: Multiplying the $15M Exclusion.

5. Post-OBBBA: The Tiered Schedule for 2025–2026 Startups

The One Big Beautiful Bill Act, signed July 4, 2025, changed the holding-period schedule for QSBS acquired after that date.³ For founders forming companies now or who received stock in late 2025 or 2026:

Stock issued on or before July 4, 2025 keeps the prior rules: 100% exclusion only after a full 5-year hold, $10M exclusion cap, $50M gross-asset ceiling.

For a 2026 founder considering a 2029 tender offer at 3.5 years: the 50% exclusion now applies. On a $15M gain, that's $7.5M excluded, saving roughly $1.8M in federal tax — not the full $3.6M you'd get at 5 years, but meaningful. The decision to push a deal to 4 or 5 years is now a quantified tax question, not just a negotiation question.

6. The Redemption Trap — Disqualification Through No Fault of Yours

Section 1202 has a redemption-based disqualification rule that catches founders by surprise. If the company redeems stock from you or a related party within 2 years before or after your shares were issued, those redemptions can disqualify your stock from QSBS treatment.¹

The most common trigger: companies that buy back shares from departing co-founders or advisors. If a co-founder leaves in Year 1 and the company repurchases their shares at a negotiated price, and that redemption exceeded a "significant" threshold, your stock issued around that time may be tainted. This isn't a theoretical risk — it's a transaction that happens at most startups. Confirm with your tax attorney that no disqualifying redemptions occurred in the window around your issuance date.

Five Questions to Confirm Before Your Deal Closes

1. Was the company a C-corp on the exact date you received your shares? If the company started as an LLC or S-corp and converted, confirm which shares were issued after the conversion and their exact issuance dates.
2. Did you file an 83(b) election within 30 days of your restricted stock grant? This is binary — confirm it was filed and sent to the IRS, with proof of mailing or submission.
3. What is your actual holding period? Not the company's age, not your grant date — the date on which each tranche of stock was legally issued to you (grant date with 83(b), vesting dates without).
4. Were the company's gross assets under the ceiling at the time of your issuance? $75M for stock acquired after July 4, 2025; $50M for earlier stock. This is measured at issuance, not at exit — a company that grew large since your grant can still qualify.
5. Were there any disqualifying redemptions within 2 years before or after your issuance? Ask your attorney to review the cap table and any repurchase transactions around your grant date.

Sources

1. IRC § 1202 — Partial exclusion for gain from certain small business stock: C-corp requirement at issuance, original-issuance test, gross-asset ceiling, holding-period rules, redemption disqualification provisions, and 28% rate on unexcluded gain.
2. Hanson Bridgett — The Importance of 83(b) Elections for Qualified Small Business Stock: Interaction of §83(b) election and QSBS holding-period start date; vesting-tranche risk for founders without an election; 30-day filing deadline.
3. Mintz — QSBS Benefits Expanded Under One Big Beautiful Bill Act: OBBBA tiered exclusion schedule (50%/75%/100% at 3/4/5+ years), $15M cap, $75M gross-asset threshold, effective date July 4, 2025.
4. Dahl Law Group — Should You Convert Your LLC or S Corporation to a C Corporation to Use QSBS Tax Benefits?: Original-issuance requirement for converting entities; holding period resets at conversion; pre-conversion interests do not qualify.

QSBS / §1202 eligibility is highly fact-specific and depends on the history of each stock grant. This guide covers the most common founder-specific issues as of 2026, including post-OBBBA changes effective July 4, 2025. Confirm your eligibility with qualified tax counsel before any liquidity event. State conformity varies — California, Oregon, DC, Pennsylvania, Alabama, and Mississippi do not conform to §1202.