Early Exercise of Stock Options: 83(b), AMT and QSBS Clocks

Is early exercise of stock options worth it?

Early exercise is worth weighing when the spread is small, because an 83(b) election then locks in little or no taxable income and starts the holding clocks early. The price is cash paid for shares you could still lose. For NSOs the election must be filed within 30 days of exercise and cannot be revoked except for a mistake of fact; a drop in value does not count.

A case is not simple when the grant mixes ISOs and NSOs or crosses the annual ISO limit, when the company's value is already above your exercise price, when you may leave before vesting, or when you live outside the US. Gather the grant agreement, the early exercise (restricted stock purchase) agreement, the company's fair market value per share on the exercise date, and proof of payment.

What is early exercise, and what do I own afterward?

Early exercise means paying the exercise price for option shares before they vest. You own the shares, but if you leave before they vest, the purchase agreement lets the company buy back the unvested ones at the price it sets, often what you paid. When that price is below the shares' value, such as what you paid, the unvested shares are "substantially nonvested": subject to a substantial risk of forfeiture because you must keep working to keep them. A buyback at full value is not such a risk (26 CFR 1.83-3(c)).

The option is gone; what you hold is restricted stock. That is why the restricted property rules, and the 83(b) election, come into play. For a normal exercise of options that have already vested, see exercising startup stock options.

Why file an 83(b) after early exercising NSOs?

An 83(b) election makes you taxed on the shares at exercise instead of at each vesting date. Without it, every vesting date is a taxable event: you report the shares' value on that date, minus what you paid, as pay (Publication 525).

With the election, you report the value at exercise minus the price paid, and later growth is not pay (26 CFR 1.83-2(a)). The regulation says the election is available even when you paid full value, so a zero-income election is still an election. Your basis is the price paid plus any income reported.

The election must be filed with the IRS within 30 days after the shares are transferred to you, and a copy goes to the company. How to file Form 15620, where to mail it and what happens if the deadline passed are covered in founder shares that vest.

Does an 83(b) matter for early-exercised ISOs?

For regular income tax, no. Section 83 does not apply when you exercise an ISO, so an 83(b) election has no regular-tax effect (26 CFR 1.422-1(b)(3), Example 2). For the alternative minimum tax, yes: the same regulation says the election is permissible for AMT purposes.

The Form 6251 instructions (line 2i) explain both paths. Without an election, the AMT adjustment is the value when the shares vest minus the price paid. With an election made by the 30th day after transfer, the adjustment is the value at exercise minus the price, even though the shares are unvested. When the price equals the value at exercise, that adjustment is zero. Form 3921 shows the value at exercise; without the election, use the value at vesting instead. Your AMT basis rises by any adjustment, so keep separate AMT and regular-tax records.

To size the AMT on a larger spread, see AMT on incentive stock options.

Can early exercise push my ISOs over the annual ISO limit?

Yes, and often at grant. Only $100,000 of stock, valued at grant, can first become exercisable as ISOs in a calendar year; the rest is treated as NSOs (26 CFR 1.422-4).

The test looks at when the option can be exercised, not when the shares vest. A grant you may early exercise is exercisable in full on day one, so the whole grant counts in the grant year. A grant that becomes exercisable only as it vests spreads across several years.

The part over the limit is an NSO for every purpose. For those shares, the regular-tax 83(b) election matters again. Unless the company designates which shares are which, the first shares you buy are treated as the ISO shares, up to the limit (26 CFR 1.422-4(c)(2)). Check Form 3921 and the company's records to see the split.

When does the long-term capital gains clock start?

With an 83(b) election, the holding period starts just after the shares are transferred to you, that is, the day after exercise (26 CFR 1.83-4(a)). Without it, each block of shares starts its clock when it vests. A gain is long-term after the shares are held more than one year.

ISO shares count as transferred at exercise even while they can still be forfeited (26 CFR 1.421-1(g)). That starts the ISO holding test: no sale until two years after grant and one year after exercise (26 CFR 1.422-1(a)).

A trap: if you sell early-exercised ISO shares before that test is met, the regulation measures your pay at the value on the vesting date, not at exercise, and the capital gain clock runs from vesting (1.422-1(b)(3), Example 2). Early exercise then gives no tax benefit for those shares. The sale rules are in exercising startup stock options.

Does early exercise start the QSBS clock?

As the rules read, yes for shares covered by an 83(b) election. The qualified small business stock tiers count how long you hold the stock, and section 1202(a)(6)(B) dates your acquisition from the first day you hold it under the general holding period rules (Public Law 119-21, section 70431). With an 83(b), that holding period starts just after exercise (26 CFR 1.83-4(a)).

For stock acquired after July 4, 2025, the exclusion is 50% after three years, 75% after four and 100% after five. So a start date earlier by a year or more can change the tier.

Two limits on that answer. No IRS ruling or regulation addresses the QSBS clock for unvested option shares, so the exercise-date start rests on the general rules above. For NSO shares without an 83(b), the clock appears to start at each vesting date; for early-exercised ISO shares, the transfer at exercise points to the exercise date, but that too is untested. Whether the stock qualifies at all depends on the company: see QSBS for founders and early employees.

What if the 409A value is already above my exercise price?

Then early exercise is no longer free. For NSOs, an 83(b) makes the spread at exercise taxable as pay now, even though the shares may never vest (26 CFR 1.83-2(a)). For ISOs with the AMT election, that spread becomes an AMT adjustment now (Form 6251 instructions).

The trade-off is a known tax today against an unknown tax at each vesting date. If the value keeps rising, the vesting-date amounts are larger. If the shares are later forfeited, the income you reported does not come back as a deduction; if they only lose value, it is part of your basis and comes back as a capital loss on sale or worthlessness (see the next section). That makes this a judgment call, not a rule. The value that counts is the company's fair market value per share on the exercise date, often called the 409A value.

What do I lose if I leave before vesting or the company fails?

If you leave, the company can buy back your unvested shares under the purchase agreement. With an 83(b) in effect, the forfeiture is treated as a sale, and your loss is limited to what you paid minus what you got back (26 CFR 1.83-2(a)). Repurchase at your cost means no gain and no loss. Any income you reported on the election is not deductible.

The regulation's loss rule is written for the section 83(b) election. How an AMT election on ISO shares unwinds on forfeiture is not spelled out, so have that reviewed if you paid AMT on a spread.

If the company fails while you hold the shares, the price you paid (plus any income reported) is generally a capital loss in the year the shares become worthless. When and how to claim it, including a possible ordinary loss, is in deducting shares in a failed startup. If you already owe tax on shares that lost value, see taxed on stock options that lost value.

What do I keep for my tax records?

Keep the papers that prove the date, the price, the value and the election. You will need them when you sell, possibly many years later.

• The option grant and plan, showing ISO or NSO status and the early exercise right
• The early exercise or restricted stock purchase agreement and its vesting schedule
• The company's fair market value per share on the exercise date and the valuation it came from
• Proof of payment of the exercise price
• A signed copy of the 83(b) or AMT election, proof of when it was sent, and the copy given to the company
• Form 3921, which the company must file and give you for each ISO exercise (Form 3921 instructions)
• A running record of regular-tax and AMT basis for each block of shares
• Any repurchase notice and payment if you leave

Example

These examples are illustrative and use US dollars.

NSOs early exercised at no spread

An employee holds 40,000 NSOs at $0.50, and the company's value per share is also $0.50. She pays $20,000 to early exercise and files an 83(b) within 30 days showing zero income. Her basis is $20,000. The long-term clock and, as the rules read, the QSBS clock start the day after exercise. Nothing is taxed as the shares vest.

ISOs over the annual limit

An employee receives ISOs on stock worth $150,000 at grant, all exercisable at grant under an early exercise feature. With no other ISOs that year, only $100,000 of that grant can be ISOs in the grant year; options on the other $50,000 are treated as NSOs. If he early exercises everything, the $50,000 NSO part needs the regular-tax 83(b) election, and the ISO part needs the AMT election, to fix both at the value on the exercise date.

Leaving after one year

The employee in the first example leaves after one year with 10,000 shares vested. The company buys back the 30,000 unvested shares at $0.50, returning $15,000. With the 83(b) in effect, her loss is $15,000 paid minus $15,000 returned: zero, so no deduction follows. She keeps the 10,000 vested shares, with $5,000 of basis and a holding period from exercise.

Different for you?

• You are exercising options that have already vested: see exercising startup stock options.
• Your ISO spread is large enough to raise AMT, or your state has its own: see AMT on incentive stock options and get individual tax help.
• You missed the 30-day deadline or need to file the election: see founder shares that vest.
• You need to know if your shares qualify for QSBS: see QSBS for founders and early employees and state tax on QSBS gains.
• You are leaving and holding vested options: see exercising stock options when you leave a startup.
• The company failed: see deducting shares in a failed startup.
• You live and work in Canada: see stock options for employees in Canada and get cross-border tax help.
• Your grant mixes ISOs and NSOs, the value is above your price, or you paid tax on shares you then forfeited: get individual tax help.