Employee equity
ISO and NSO stock options explained
Understand US incentive and nonstatutory stock option classifications, the difference between exercise cost and tax, and the records the app tracks.
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Two classifications in the US tax system
Incentive stock options, or ISOs, and nonstatutory stock options, often called NSOs, have different US federal tax rules. A qualifying ISO must satisfy statutory conditions; marking a grant ISO in software does not make it qualify.
The IRS explains the distinction in Topic 427: Stock options. State rules, international arrangements, and an individual’s circumstances require separate analysis.
Exercise cost and taxable amounts are different
Suppose a holder exercises 2,000 options at a $3 strike when shares have an $8 FMV. The exercise purchase price is 2,000 × $3 = $6,000. The spread is 2,000 × ($8 − $3) = $10,000. Neither number alone is the tax owed.
The IRS notes that ISO exercise can create an alternative minimum tax adjustment. For a typical nonstatutory option without readily determinable value at grant, exercise generally produces income based on the spread. Sale timing and qualification can affect later treatment. Do not turn this example into a tax-rate calculation without the relevant facts.
Keep the qualifying facts with the grant
Employee status, grant terms, pricing, exercise timing, and holding periods can matter. The ISO annual limit considers grant-date value of stock first exercisable in a calendar year, rather than simply the number of options granted that year. Cooley’s ISO and NSO comparison discusses qualifying conditions and distinctions.
Cap Table offers classification fields and an ISO-limit check. These are recordkeeping and review tools, not a complete determination of tax qualification across every employer plan or later event.
Retain the exercise evidence
Keep the grant agreement, classification, grant-date valuation, exercise notice, payment evidence, certificate, and exercise-date FMV connected. Review classification if actual terms or employment circumstances change.
The app’s Form 3921 report organizes recorded ISO exercise certificates. NSO exercises do not become Form 3921 rows simply because they create shares. Payroll, withholding, and personal tax reporting remain separate workflows.