Founder Stock and Section 83(b): How the 30-Day Election Works and the Mistakes That Cannot Be Undone

A typical stock purchase agreement lets the company repurchase unvested shares at cost if the founder leaves, with that right lapsing over four years. For federal tax purposes, the repurchase right usually makes the shares substantially nonvested under Section 83, so the default rule taxes each tranche as it vests on the excess of its vesting-date value over the price paid for it.

A Section 83(b) election replaces that default with a single measurement at issuance. For founders who pay full value at formation, the decision is usually straightforward; the execution is not. The statute allows 30 days with no extension procedure, and the filing leaves a paper trail that investors and acquirers test years later. If the window has already closed, start with what can still be done after a missed 83(b) deadline.

1. What the Election Changes

Under 26 U.S.C. §83(a), property transferred in connection with services is taxed when it first becomes transferable or is no longer subject to a substantial risk of forfeiture, measured as fair market value at that time less the amount paid. Section 83(b)(1) lets the service provider elect instead to include value at the time of transfer, determined without regard to lapse restrictions such as vesting. Treas. Reg. §1.83-2(a) confirms that paying full value does not preclude the election, so a founder who buys shares at current value can make a zero-income election.

The trade-off is forfeiture risk. A zero-income election risks little; one reporting meaningful income is a bet that the founder stays and the shares appreciate.

2. Computing the 30-Day Deadline

Section 83(b)(2) requires the election no later than 30 days after the date of transfer, which is when the founder acquires beneficial ownership (Treas. Reg. §1.83-3(a)(1)). If the purchase agreement, board consent, and stock ledger show different dates, compute the deadline from the earliest one and resolve the discrepancy with counsel. Count from the day after the transfer. The April 2025 Form 15620 instructions apply Section 7503: when day 30 falls on a Saturday, Sunday, or legal holiday, an election postmarked on the next business day is timely. The election still relates to the taxable year that includes the transfer.

Treat the weekend rule as a backstop. Treas. Reg. §301.9100-1(b) classifies an election whose due date is prescribed by statute as a statutory election; relief under §301.9100-3 is limited to regulatory elections, and §301.9100-2 covers only elections due with a return. Revocation is also narrow. Under Rev. Proc. 2006-31, a revocation request filed within the 30-day window will generally be granted through the letter-ruling process. Afterward, consent requires a mistake of fact about the underlying transaction, raised within 60 days of discovery; a mistake about value, a decline in value, or a misunderstood tax result does not qualify.

3. Filing Methods as of October 2026

The election can be made on Form 15620 (Rev. April 2025) or a signed statement that says it is made under Section 83(b) and contains the items in Treas. Reg. §1.83-2(e): name, address, and TIN; the property; the transfer date and taxable year; the restrictions; value at transfer; the amount paid; and a statement that the required copies were furnished.

• Online. The IRS mobile-friendly forms page lists Form 15620 as requiring an IRS Online Account; a completed form can be submitted online or downloaded for mailing, and a successful submission returns a success message and a download link. Save both.
• Mail. The Form 15620 instructions describe mailing to the IRS office where the founder files a return, and Publication 525 (2025) points to the Form 1040 address for returns without a payment. Use certified or registered mail, or a designated private delivery service. Under Treas. Reg. §301.7502-1(e)(2), apart from direct proof of actual delivery, those are the exclusive ways to establish prima facie evidence of delivery.
• One channel per election. Choose online or mail, not both. A founder abroad can mail the election, but the timely-mailing rule does not cover mail deposited with a foreign postal service (Treas. Reg. §301.7502-1(c)(1)(ii)).

Treas. Reg. §1.83-2(d) also requires a copy to the company and, if someone other than the founder receives the shares, such as a trust, to that transferee. Since T.D. 9779, a copy no longer has to be attached to the return for property transferred on or after January 1, 2016, so keep the founder's copy for as long as the income or basis matters.

4. Valuation: The Number That Drives the Election

At formation, before outside capital or meaningful assets, value often equals the purchase price. Shares issued to a co-founder who joins after a SAFE financing, a product launch, or the first customer contracts may be worth materially more than the price paid, and the excess is compensation income for the transfer year (generally wages for an employee-founder).

The election fixes timing, not value. Section 83(b)(1) measures income by actual fair market value at transfer, so an understated figure does not bind the IRS, and Treas. Reg. §1.83-2(f) excludes a mistake as to value from the grounds for revocation. Support the number with a board determination, a recent independent common-stock valuation when one exists, and a short memo.

5. Early-Exercised Options

The grant of an option is not a transfer of the stock (Treas. Reg. §1.83-3(a)(2)), and Publication 525 states that the election cannot be made for a statutory or nonstatutory option. When a plan allows early exercise, the holder buys unvested shares subject to repurchase, and the 30-day window runs from the exercise date, not the grant date.

• Nonqualified options. With an election, compensation income is the spread at exercise, often zero when exercise follows soon after a grant priced at fair market value.
• Incentive stock options. Section 56(b)(3) turns off Section 421 for alternative minimum tax (AMT) purposes, and Publication 525 places the AMT adjustment at vesting, cross-referencing its restricted property rules; an election within 30 days of an early exercise is commonly filed to measure it at exercise instead. Under Section 422(d) and Treas. Reg. §1.422-4(b)(4), an option exercisable in full at grant generally counts entirely toward the $100,000 limit in the grant year. See ISO and AMT planning for 2026.
• Exercise with a note. A nonrecourse note secured by the shares may make the arrangement an option in substance under Treas. Reg. §1.83-3(a)(2), leaving no transfer to elect on.

6. LLC Profits Interests Follow a Different Framework

A capital interest in an LLC taxed as a partnership is commonly analyzed like restricted stock. A profits interest is different. As summarized in Rev. Proc. 2001-43, Rev. Proc. 93-27 generally does not treat receipt of a profits interest for services in a partner capacity, or in anticipation of becoming a partner, as a taxable event, subject to stated exceptions. Rev. Proc. 2001-43 then treats an unvested profits interest as received at grant and states that taxpayers within its scope "need not file an election under section 83(b)," provided the holder is treated as a partner from grant, reports a distributive share throughout, no one deducts the interest's value, and the other Rev. Proc. 93-27 conditions are met.

Because those conditions can change, many advisers file a protective zero-value election within 30 days of grant. Proposed regulations from 2005 (REG-105346-03, with Notice 2005-43) would apply Section 83 directly to partnership interests; no final rule had been published in the Federal Register as of October 17, 2026. Partnership interests also cannot be qualified small business stock; see S corporation versus C corporation for founders raising capital.

7. Hypothetical Example: One Founder, Two Outcomes

8. Build the Diligence File Now

Investors and acquirers ask for 83(b) proof, so keep these items together with the company's equity and tax records (see startup CPA services):

1. The purchase agreement, board consent, and ledger entry, all showing one transfer date.
2. Proof of payment for the shares.
3. The signed election plus the online confirmation or certified-mail receipt.
4. Evidence that the company received its copy, and the valuation support.
5. Records of later restructurings. Rev. Rul. 2007-49 holds that adding vesting to already vested shares, without an exchange, is not a Section 83 transfer, while exchanging vested shares for unvested acquirer shares is one and can open a new 30-day window.

Section 1202 raises the stakes. P.L. 119-21 §70431 added a 50%, 75%, and 100% Section 1202(a) exclusion at three, four, and five years for stock acquired after July 4, 2025. Without an election, Treas. Reg. §1.83-1(a)(1) treats the company as owner of unvested shares until vesting, creating a risk that each tranche is treated as acquired at vesting, which could delay those clocks and test gross assets later. The QSBS hygiene checklist for founders covers the remaining requirements.

Common Mistakes

• Counting from the wrong date. The clock runs from the transfer or early-exercise date, not from vesting.
• Expecting relief. Neither §301.9100-3 relief nor revocation repairs a missed or regretted election.
• Using par value by habit. Shares issued after a financing may be worth more than the price paid.
• Not giving the company a copy. The regulation requires it, and its absence becomes a diligence gap.
• Relying on ordinary mail or filing twice. Keep an online confirmation or certified-mail receipt, and use one channel.
• Treating an LLC profits interest like founder stock. Profits interests follow Rev. Proc. 93-27 and 2001-43.
• Missing a new window in a deal. An exchange into unvested acquirer shares can be a new Section 83 transfer.

The Bottom Line

For founders who buy shares at formation for their current value, a timely Section 83(b) election usually costs nothing in current tax and treats later appreciation as capital gain at sale rather than compensation at vesting. The risk is in execution: the wrong transfer date, an unsupported value, an unconfirmed filing, a missing company copy, or an equity instrument that follows different rules. File within 30 days through one documented channel, and keep the proof where an investor or acquirer can find it. For later issuances, early exercises, or LLC interests, coordinate counsel and 83(b) election support before the clock starts.

This article provides general educational information about U.S. federal tax rules for Section 83(b) elections as of October 17, 2026. It is not tax or legal advice; transfer dates, equity documents, valuation, entity classification, and state law require review of the specific facts with a CPA and counsel.