Before You Exercise Your Employee Stock Options

Questions about timing, cash requirements, tax treatment, and the risk of concentrating wealth in employer stock.

Most people first meet their stock options as a number on a screen. The statement says you hold 20,000 options, the company is doing well, and the math looks wonderful. A number on a screen is not money in your bank account, and the gap between the two is where costly mistakes happen. Exercising an option means spending your own cash to buy shares, and the IRS may expect a tax payment on that purchase before you have sold a single share. I walk clients through the same set of questions every time, and they are worth answering before you click the exercise button.

Start with the type of option you hold

The IRS sorts employee stock options into two groups. Options granted under an employee stock purchase plan or an incentive stock option plan are statutory, and every other option is nonstatutory. Your grant agreement and equity plan document will tell you which one you hold, and IRS Publication 525 explains how to sort it out if the paperwork is unclear. The distinction controls when income is recognized and what kind of income it is, so it comes before every other question. Find the document today, because every answer below changes depending on what it says.

One wrinkle surprises people. An option labeled as an ISO stops being one to the extent that stock first becoming exercisable in a calendar year is worth more than $100,000, and the excess is treated as nonstatutory. The value is measured at the time of the grant, and it counts across all plans of the employer and related corporations. A single grant can therefore be part ISO and part NSO, with each slice taxed under its own rules. Ask your plan administrator for a breakdown so you are not guessing which shares are which.

Timing is a question of three clocks

Three clocks run at once. The first is your vesting schedule, which controls when you are allowed to exercise. The second is the expiration date, and for ISOs the option must be exercised within ten years of the grant date. The third is your employment, and it is the one people forget until a job change forces the issue. To keep ISO treatment you generally must exercise within three months of leaving, which stretches to twelve months for total and permanent disability, while an NSO window is whatever your plan says and can be shorter or much longer.

Once you leave, the cash decision gets compressed into a few weeks. People who planned nothing find themselves choosing between writing a large check and walking away from options they spent years earning. If there is any chance you will change jobs, work out the cost of exercising now, while you still have a paycheck and time to think. Your plan may also have blackout periods around earnings announcements, so the day you want to exercise might not be a day you are permitted to sell. Read the plan rules on blackout windows and exercise methods early.

Calendar timing matters as well. Income from an NSO exercise and the AMT adjustment from an ISO exercise both land in the year you exercise, so exercising everything in a single high income year can cost more than spreading the exercises across two or more years. A December exercise and a January exercise are taxed in different years, which gives you room to plan around bonuses, a spouse's income, or the sale of other assets. The holding period clock for ISOs also begins on the exercise date, so a later date pushes out the day you qualify for favorable treatment. A tax projection for the current year, run before you exercise, is the tool that settles which date makes sense.

Some companies, mostly private ones, allow you to exercise before your options vest. When you do, you must file an 83(b) election with the IRS within thirty days, and missing that deadline costs you the tax benefit. The IRS introduced a standardized Form 15620 for this election in 2024. Early exercise is attractive when the spread between your price and the current value is small, since you owe little tax and the capital gains clock starts early. It carries risk, because you are paying cash for shares that may never be worth more than you paid, and an early exercised ISO may no longer qualify for ISO treatment and be taxed like an NSO. Treat the thirty day deadline as firm and have your CPA review the election before it is mailed.

How much cash you will need

There are two bills, and they arrive close together. The first is the exercise price multiplied by the number of shares, and the second is the tax. Suppose you hold 10,000 options with a strike price of $5 and the shares are worth $25 on the day you exercise. You pay $50,000 to buy the shares, and the $200,000 spread between value and cost is where the tax question begins. The numbers are illustrative, but the structure applies to every exercise.

Many public companies offer a cashless exercise or a sell to cover arrangement, where some of the shares are sold immediately to pay the exercise price and the taxes. Your plan has to allow it, so check which methods are available to you. Private companies usually offer no market for the shares, which means you may owe tax on a gain you cannot turn into cash for years, if ever. I would not want a client to drain an emergency fund or borrow against retirement savings to fund an exercise, because the shares can lose value after you buy them while the tax you paid stays paid. If the cash is not available without strain, exercising a smaller portion is a sound choice.

The tax side needs a plan too. For an NSO the spread is wages, and employers generally withhold a flat 22 percent on supplemental wages up to $1 million in a calendar year and 37 percent on the excess. If your marginal bracket is higher than 22 percent, that withholding falls short and the difference is due when you file. For 2026, the 32 percent bracket applies to income over $201,775 for single filers and $403,550 for married couples filing jointly, so many people exercising a meaningful number of options are above the flat rate. An ISO exercise has no withholding at all, so any AMT it creates has to be covered through estimated payments or additional withholding from your paycheck. To avoid an underpayment penalty you generally need to pay in at least 90 percent of this year's tax or 100 percent of last year's, and that rises to 110 percent of last year's when prior year adjusted gross income exceeded $150,000.

How the tax works for ISOs

With an ISO you generally include nothing in gross income when the option is granted or exercised, and your taxable gain or loss is determined when you sell the shares. If you hold the shares for at least two years after the grant date and more than one year after the exercise date, the profit is generally a long term capital gain. Selling before those periods are met is a disqualifying disposition, and the exercise is then treated as the exercise of a nonstatutory option, producing compensation income in the year of sale. Your employer reports the exercise on Form 3921, which lists the dates and values you need at filing time. Keep every Form 3921 until well after the shares are gone.

The catch is the alternative minimum tax. You may owe AMT in the year you exercise an ISO even though you have not sold anything, because the spread at exercise is added into AMT income. The adjustment is reported on Form 6251 and increases your AMT basis in the shares by the same amount, though no adjustment is needed if you dispose of the stock in the same year you exercise. For 2026 the AMT exemption is $90,100 for single filers and $140,200 for married couples filing jointly, and it begins to phase out at $500,000 and $1,000,000 of AMT income. Under the 2025 tax law, the phaseout rate doubled to 50 percent, so a large spread can erase the exemption faster than it used to. AMT depends on your whole return, so run the numbers with your CPA before the exercise date and keep careful records, since AMT paid on an ISO exercise can often be recovered in later years through the credit for prior year minimum tax.

How the tax works for NSOs

With a typical NSO there is no tax at grant, but at exercise you include the value of the shares less what you paid in income, and a later sale produces a capital gain or loss. That spread is wages, so it appears on your W-2 and is included in the boxes that report taxable wages as well as Social Security and Medicare wages. High earners also owe the additional Medicare tax of 0.9 percent on wages above $200,000 for single filers and $250,000 for married couples filing jointly. Your basis in the shares equals the value on which you were taxed at exercise, which means only growth after that date is taxed as a gain. Holding the shares for more than one year after exercise makes that later growth a long term gain, while a shorter hold makes it short term.

State taxes belong in the picture as well. Florida has no state income tax on wages, which many of my clients in Palm Beach County appreciate, so the federal calculation is most of the story for Floridians. If you live in or are planning a move to a state that taxes income, an exercise can add a meaningful state bill, and the rules for dividing option income between states get complicated when you have lived in more than one. Raise any planned move with your CPA before you exercise, since the date of the exercise relative to the move may matter.

The risk of putting too much of your wealth in one company

FINRA describes concentration risk as the amplified loss that can come from holding a large portion of your holdings in one investment, and it lists company stock as a common way it occurs. Your employer already controls your paycheck and often your bonus, health coverage, and retirement match. When you add a large block of its shares, a bad quarter, a lawsuit, or a round of layoffs can hit your income and your savings in the same month. That overlap is what makes employer stock riskier than the same dollars in an unrelated company. A strong company can still fall, and the people holding the most shares feel it hardest.

There is no set definition of a concentrated position, and one simple approach is to trim the holding below a target threshold such as ten percent. Count everything you own that depends on that employer, including shares in your 401(k), shares from a purchase plan, vested options, and unvested grants you expect to receive. Many people find the total is larger than they assumed once every source is added up. A figure like ten percent is a starting point for a conversation with your advisor rather than a rule written in the tax code. Your age, your other assets, and your need for cash all move the right number up or down.

Taxes can make people hold on to shares longer than is wise. Waiting out the ISO holding periods keeps the capital gains rate in play, but Fidelity points out that when the goal is to meet a cash need or reduce a single stock concentration, a disqualifying disposition can outweigh the tax benefit of holding. Selling some shares at exercise or soon after locks in a gain while the price is favorable, and the proceeds can move into diversified funds, which FINRA says can help achieve broad diversification. Paying some extra tax in exchange for lower risk is a trade many clients decide is worth making. The goal is to decide that trade on purpose rather than let the tax tail wag the investment dog.

Questions to settle before you exercise

Before the exercise button gets clicked, write down answers to a short list of questions. Which type of option is this, and does any part of the grant exceed the ISO limit? When does it expire, and what happens to it if you leave? What will the shares cost, what will the tax cost for this year, and where will that cash come from? What share of your total wealth will be tied to this one employer afterward, and when do you plan to sell? Bring those answers, your Form 3921 or W-2 history, and your grant documents to a meeting with your CPA, since a projection built on your own return is worth more than any general rule.

General information like this cannot account for your income, your state, your family situation, or the terms of your particular plan, and equity compensation rules carry exceptions. Good decisions here tend to be made months before an expiration date rather than in the final week. A conversation with a CPA and a financial advisor before you exercise costs far less than correcting a problem afterward, and an exercise usually cannot be undone. Your equity may turn out to be a meaningful part of your financial future, and it deserves a plan as careful as the work that earned it.