This article is for educational purposes only and does not constitute personalized financial, tax, or investment advice. Willcox Wealth Management is a registered investment adviser. Please consult with a qualified professional before making financial decisions based on the information presented here.

Incentive Stock Options: What You Need to Know Before You Exercise

If you’ve been granted Incentive Stock Options at work, you’ve probably been told they’re valuable. And they can be. But there’s a gap between “you have stock options” and actually knowing what to do with them, especially when it comes to taxes.

I’m not going to give you specific advice here. Everyone’s situation is different. What I want to do is walk through the mechanics so that when it’s time to make decisions, you’re not starting from scratch.

What Is a Stock Option?

A stock option gives you the right to buy your company’s stock at a set price, called the strike price (or exercise price). If your strike price is $5, you pay $5 per share. That’s the deal, regardless of what the stock is actually worth on the open market.

The upside comes when the stock’s fair market value rises above your strike price. FMV goes to $6? You can buy a $6 stock for $5. That’s a dollar per share in your pocket. You can sell right away and take the gain, or hold on and see where it goes.

Simple enough so far. The taxes are where people’s eyes start to glaze over.

Exercising Doesn’t Trigger Regular Tax

When you exercise, you’re just buying stock at the strike price. You haven’t sold anything. There’s no cash hitting your bank account. So for regular federal income tax purposes, nothing happens. No taxable event.

The tax bill shows up when you sell.

How the Sale Gets Taxed

This part depends on timing.

If you exercise and sell right away, the spread between your strike price and the FMV gets taxed as ordinary income. Same rates as your salary. The IRS treats this as a disqualifying disposition because you didn’t hold the shares long enough to get any special treatment.

If you hold the shares for at least one year after exercise and two years from the grant date, you qualify for long-term capital gains rates on the full gain. That’s a qualifying disposition. The rate difference can be significant. Someone in the 35% or 37% tax bracket paying 15% or 20% on the same gain instead? That’s real money.

AMT: The Part Nobody Warned You About

If it ended there, ISOs would be pretty clean. Exercise, hold for a year and two years, sell at capital gains rates. Done.

But there’s a parallel tax system called the Alternative Minimum Tax, and it sees your ISO exercise very differently than the regular tax code does.

For most people, AMT never comes up. Their regular tax bill is higher, they pay that, end of story. But certain income items can flip the math. Exercising ISOs is one of the most common triggers.

The spread at exercise — FMV minus strike price, times the number of shares — counts as income under the AMT calculation, even though it’s invisible to the regular tax system. If that number pushes your AMT above your regular tax, you pay the higher amount.

What That Actually Looks Like

Say you have ISOs with a $5 strike price. The stock is at $25 when you exercise 5,000 shares. That’s a $20 per share spread, or $100,000 total. Under the regular tax rules, that $100,000 doesn’t exist yet. Under AMT, it absolutely does.

For a single filer in 2026, the AMT exemption is $90,100. If you’re already earning a solid salary, that extra $100,000 in AMT income can blow right past the exemption. Now you owe tax on gains you haven’t actually pocketed.

(This is a simplified, hypothetical illustration. Actual AMT depends on your full income, filing status, deductions, and a bunch of other variables.)

The Cash Crunch

This is the part that catches people off guard. You exercised because you want to hold the stock. Maybe you believe in the company, maybe you’re trying to hit that one-year mark for capital gains treatment. Either way, you don’t want to sell yet.

But the IRS wants money now. On gains that are still just numbers on a screen.

If you exercised a big block of shares, that AMT bill can be substantial. And you need cash to pay it. That tension between wanting to hold and needing liquidity to cover the tax is one of the trickiest parts of ISO planning.

AMT Credits: You Can Get It Back

One piece of good news. AMT paid because of ISO exercises generates a credit you can carry forward and use in future years. When your regular tax exceeds your tentative minimum tax down the road, you apply the credit and bring your bill down. The credit never expires.

It doesn’t fix the short-term cash problem. You still need the money now. But over time, you can recover some or all of what you paid. Think of it less as a tax and more as a forced prepayment you’ll eventually claw back.

Why This Matters for Planning

With some upfront modeling, we can usually get a pretty good read on whether a given exercise will trigger AMT and roughly how much. That changes the whole conversation. Instead of getting surprised with a bill in April, you can spread exercises across years to stay under the AMT line, time them around other income, and make sure you have the liquidity to cover what’s owed without being forced into a sale you don’t want to make.

None of it is one-size-fits-all. But the worst version of this story is finding out what you owe after it’s too late to do anything about it.