Equity compensation is one of the most powerful wealth-building tools available to executives — and one of the most misunderstood. The difference between RSUs and ISOs isn't just technical jargon: it can represent hundreds of thousands of dollars in taxes paid or deferred over the course of a career. We regularly see executives arrive at a planning conversation having never exercised their ISOs strategically, missed opportunities to hold qualifying shares, or sold RSU lots without any awareness of their embedded tax liability. The foundation of good equity planning is understanding what you have and what choices are actually available to you.
Understanding RSUs
Restricted Stock Units are the most common form of equity compensation at public companies today. When a company grants you RSUs, it is promising to deliver actual shares — or their cash equivalent — when certain conditions are met, most commonly a time-based vesting schedule. Unlike stock options, RSUs don't require you to purchase anything. The shares are simply delivered to you when you vest.
The tax treatment is straightforward, and that simplicity comes at a cost. On the date your RSUs vest, the fair market value of the shares delivered is recognized as ordinary income. It is reported on your W-2 and subject to federal income tax at your marginal rate, Social Security taxes, and Medicare taxes — including the additional 0.9% Medicare surtax if your income exceeds applicable thresholds. Your employer is required to withhold taxes, typically by selling a portion of the vested shares at the time of vest. This is called "sell-to-cover" withholding.
What many executives miss is the double-tax trap at sale. Your cost basis in the shares is set at the fair market value on the vest date — the same amount already taxed as ordinary income. If you hold the shares and they appreciate, you will owe capital gains tax on any additional appreciation when you eventually sell. If the shares have declined since vesting, you have a capital loss — but you've already paid ordinary income tax on the higher value. This is why holding vested RSU shares without a plan is a form of concentrated risk that is often uncompensated.
RSUs are relatively inflexible. There are no exercise decisions to make, no timing elections that affect the ordinary income recognition event. Your primary planning levers are: managing when you sell (to optimize long-term vs. short-term capital gains), whether to use charitable strategies such as contributing shares to a donor-advised fund, and how RSU income interacts with your other deductions and credits in a given tax year.
Understanding ISOs
Incentive Stock Options are considerably more complex — and considerably more valuable when managed correctly. An ISO gives you the right to purchase company stock at a specified price (the exercise or strike price) for a set period, typically up to 10 years. The potential for preferential tax treatment is meaningful: if you follow the holding period rules, the spread between your strike price and the eventual sale price can be taxed at long-term capital gains rates rather than ordinary income rates, potentially saving you 20 to 25 percentage points on federal taxes alone.
The mechanics work as follows. At grant, no tax event occurs. At exercise — when you pay the strike price and receive the shares — no regular income tax is due. This is the fundamental advantage. However, the spread at exercise (fair market value minus exercise price) is an "AMT preference item" and is added to your Alternative Minimum Tax income. Depending on your overall income picture, exercising a significant number of ISOs in a single year can create a substantial AMT liability.
To receive long-term capital gains treatment on the full gain, you must meet both of these holding period requirements: hold the shares for at least two years after the grant date, and at least one year after the exercise date. If you sell before meeting these requirements, you have a disqualifying disposition: the spread at exercise is treated as ordinary income, and any additional appreciation is a short-term or long-term capital gain depending on how long you held after exercise. A disqualifying disposition is often the right choice — but it should be a deliberate one, not an accidental one.
ISOs also carry an annual limit: only $100,000 worth of ISOs (measured by the exercise price at grant) can become exercisable for the first time in any calendar year and retain ISO status. Options that exceed this limit are treated as Non-Qualified Stock Options (NSOs).
NSOs: The Default Option Type
Non-Qualified Stock Options — sometimes called NQSOs — are the catch-all option type. Any option that does not qualify as an ISO is an NSO. They can be granted to employees, directors, contractors, and others. At exercise, the spread (fair market value minus exercise price) is recognized as ordinary income, reported on your W-2 or 1099, and subject to income and payroll taxes. After exercise, any subsequent gain or loss is a capital gain or loss, long-term or short-term depending on your holding period. NSOs offer no AMT complexity but also no preferential tax treatment on the spread.
The Key Planning Differences
The core distinction in planning terms comes down to four variables: when income is recognized, AMT exposure, the potential for capital gains treatment, and QSBS eligibility.
Timing of income recognition. RSUs trigger income at vest — you have no control over this. ISO exercises can be timed deliberately: you choose when to exercise, and that decision drives both your AMT exposure and your holding period clock. NSO exercises are similarly elective, but the income is ordinary regardless of timing.
AMT exposure. RSUs carry no AMT implications. NSOs carry none either. ISOs are the only equity instrument that creates AMT preference income at exercise, and for executives with large option grants — particularly pre-IPO — this can result in significant AMT liabilities that require careful modeling before any exercise decision.
Capital gains potential. RSUs produce ordinary income at vest; any subsequent appreciation is capital gain. ISOs can produce all-long-term-capital-gains treatment on the entire spread from strike price to sale price, if holding periods are met. NSOs produce ordinary income on the spread, capital gains on post-exercise appreciation only.
QSBS eligibility. Under IRC Section 1202, gain from the sale of Qualified Small Business Stock can be excluded from federal tax (up to $10 million or 10x your basis, whichever is greater) if shares are held for more than five years and other requirements are met. ISO shares acquired from an eligible C-corporation can qualify. RSUs delivered as shares can also qualify, but the five-year clock starts at vest. QSBS planning is a high-value area that deserves its own analysis — the tax savings potential is extraordinary for executives at qualifying startups. Learn more about our equity compensation planning services.
2026 Planning Considerations
The current tax environment makes equity planning more consequential than in prior years. Ordinary income tax rates remain elevated at the top end, and the gap between ordinary income rates and long-term capital gains rates continues to make deferral and conversion strategies worthwhile. For high-income earners, the combined federal rate on ordinary income — including the Net Investment Income Tax and the additional Medicare surtax — can approach or exceed 40% in some states.
AMT exemption phaseouts are relevant for executives with large ISO grants. While the AMT exemption amounts are substantial, they phase out at higher income levels, meaning the effective AMT rate can be higher than the statutory 26%–28% rates for some taxpayers. Running an AMT projection before any ISO exercise is not optional — it is essential.
State taxes compound the analysis significantly. California, in particular, does not conform to the federal ISO preference: California taxes ISOs at exercise, treating the spread as ordinary income for state tax purposes regardless of federal AMT treatment. Executives in California — or those who lived in California when ISOs were granted — need to factor this in before assuming the "ISO advantage" applies fully to their situation. New York has similar considerations.
Common Mistakes We See
The most costly mistake is exercising ISOs without AMT modeling. An executive receives a large ISO grant, the company does well, and without running projections, they exercise a large block in a single year, triggering an AMT bill they weren't prepared for. In some cases, the AMT bill exceeds their available cash, forcing a sale of shares at an inopportune time. The AMT is not unpredictable — it can be modeled precisely — but only if you do the work before exercising.
The second common mistake is failing to track cost basis for each lot. If you've been receiving RSU vests quarterly for three years, you have twelve or more separate tax lots, each with its own basis and holding period. Selling shares without knowing which lots you're selling — and without selecting the optimal lots for tax efficiency — is a significant and avoidable error. The IRS requires you to specifically identify shares for purposes of cost basis if you want to use anything other than FIFO, so working with advisors and your brokerage to set up specific identification is important.
Third, many executives ignore the interaction between equity income and other deductions. RSU income that vests in a high-income year may be better offset by charitable contributions, retirement contributions, or loss harvesting from other positions. Thinking about equity compensation in isolation — rather than as part of the full-year tax picture — leads to missed planning opportunities.
When to Work with an Advisor
If you have equity grants worth more than $500,000 — whether vested or unvested — the complexity of your situation likely warrants professional guidance. This is especially true if you hold multiple types of equity (RSUs, ISOs, and NSOs simultaneously), if your company is approaching an IPO or M&A event, or if you have any QSBS-eligible shares. Pre-liquidity planning is particularly time-sensitive: many of the most powerful strategies — early exercise elections, 83(b) elections for restricted stock, ISO exercise planning — must be executed before a liquidity event, not after.
Post-IPO is often when executives feel like they have more time to plan. In our experience, the window immediately following an IPO — particularly during and after lockup expiration — is when decisions made without careful planning are most costly. Concentrated positions, ordinary income recognition from disqualifying dispositions, state tax exposure for mobile executives: these are all live issues in the first twelve months after a company goes public.
Equity compensation is a meaningful part of total compensation for a reason. Treating it with the same rigor as the rest of your financial life — and working with an advisor who specializes in this area — is how executives convert equity grants into lasting wealth rather than tax bills.
We help executives understand their grants, model AMT exposure, and build strategies for every stage — pre-IPO to post-liquidity.
