Incentive Stock Options, AMT, and the 83(b) Election Explained

You joined a private company three years ago and received incentive stock options as part of your offer. The company has grown. Your strike price is $2 a share and the latest 409A valuation puts the common stock at $18. Exercising your options would cost $20,000 to buy shares now worth $180,000 on paper. It looks like a straightforward decision. Then your accountant mentions "alternative minimum tax" and the math changes completely.

Unlike restricted stock units, which create ordinary income the moment they vest, incentive stock options come with a quieter risk: you can trigger a five-figure or six-figure AMT bill in a year you sold nothing, received no cash, and may be unable to sell the shares at all. This post explains how ISOs, the AMT, and the 83(b) election actually work, what triggers the tax, and what you can do about it before a deadline you did not know you had passes.

What Makes Incentive Stock Options Different

Incentive stock options give you the right to buy company stock at a fixed price (the strike price) after they vest. They are not the same as RSUs, and the tax treatment diverges sharply.

With RSUs, the shares are yours when they vest. Your employer withholds a portion for taxes at the flat 22% supplemental rate (37% once your supplemental wages cross $1 million in the year), and the vest-date value is ordinary income on your W-2. The tax bill is visible and mostly paid.

ISOs work differently. You receive nothing at vest. To own the shares, you must exercise the option: write a check to the company for the strike price times the number of shares. At exercise, for regular tax purposes, nothing happens. There is no income, no withholding, no W-2 entry. The bargain element (the difference between the fair market value and your strike price) is not taxed as ordinary income.

That is the good news. The bad news is that the bargain element is an AMT preference item. And the AMT has its own set of rules.

The AMT Trap: Tax on Shares You Cannot Sell

The alternative minimum tax is a parallel tax system that runs alongside the regular income tax. You calculate your tax under both systems and pay whichever is higher. The AMT was originally designed to prevent high-income taxpayers from using deductions and preferences to pay little or no tax. But for holders of incentive stock options, it creates a specific trap.

When you exercise ISOs and hold the shares, the bargain element ($160,000 in the opening example) gets added to your AMT income. That single transaction can push you past the AMT exemption ($90,100 for a single filer in 2026, $140,200 for married filing jointly) and into a tax that applies 26% to 28% rates to income the regular tax system ignores.

Here is the important part: you owe this tax even though you have not sold a share. The company is private. There is no market for the stock. You may have no way to generate the cash for the tax bill. And once the AMT liability is triggered, it is due with your tax return the following April, just like any other tax.

For a single filer who exercises ISOs with a $160,000 bargain element and has $200,000 in regular wages, the AMT calculation in 2026 could generate an additional tax liability of roughly $34,000. Again: no shares sold, no cash received, tax bill due.

This is the moment people learn about the 83(b) election, sometimes too late. One catch up front: the election only applies when you exercise before your options vest. For options that have already vested, an 83(b) doesn't help.

The 83(b) Election: Filing Within 30 Days

An 83(b) election is a one-page letter you send to the IRS within 30 days of early exercising unvested options or receiving restricted stock. It tells the IRS: tax me now, at today's value, rather than later, when the stock vests and is worth more.

For ISO holders, the 83(b) election changes the AMT calculation. If you exercise early, when the fair market value is still close to your strike price, the bargain element is small or zero. Filing the 83(b) locks in that low value as your taxable amount for AMT purposes. The tradeoff is that you pay tax or trigger AMT earlier than you would have. But when the spread is minimal, the earlier tax bill is usually the smaller one.

The deadline is absolute: 30 days from the exercise date. The IRS does not grant extensions. Send the election by certified mail, return receipt requested. Keep the receipt. Keep a copy of the election with your tax records permanently. If you miss the window, the opportunity is gone for those shares.

The 83(b) election also starts the clock on the long-term capital gains holding period. To get qualifying ISO treatment, where you pay long-term capital gains rates instead of ordinary income rates, you must hold the shares for more than one year from the exercise date AND more than two years from the grant date. An 83(b) election does not shorten that two-year grant-date requirement, and the one-year clock runs from the exercise date, not the date you file.

When Early Exercise Makes Sense (and When It Doesn't)

Early exercise means exercising your options before they vest. Many startup option plans allow it. The strategy is simple: exercise as soon as possible, when the 409A valuation is still low, file an 83(b) election immediately, and start both the AMT clock and the capital gains holding period.

The potential tax advantage is easy to see. If your strike price is $0.50 and the current 409A is $0.55, exercising 100,000 shares costs $50,000 and generates an AMT preference item of just $5,000, which is negligible. You have now converted future appreciation from ordinary income or AMT treatment into long-term capital gains, provided you meet the holding periods.

The risks are equally real. You are writing a check for $50,000 to buy shares in a private company that could fail. If the company goes under, the stock becomes worthless, and you lose the entire investment. You may be able to claim a capital loss, but only $3,000 per year can offset ordinary income. The rest carries forward. The AMT you paid on the bargain element creates a minimum tax credit, but recovering it requires future years where your regular tax exceeds your AMT, which may take a long time if you remain a high earner.

Early exercise also uses cash you could have invested elsewhere. That is a personal decision, not a tax one, but it belongs in the same spreadsheet. A strategist who understands equity compensation can model the numbers and help you make the call, but the call is yours.

The AMT Credit: Getting Your Money Back

AMT paid because of an ISO exercise is not gone forever. It creates a minimum tax credit that can offset regular tax in future years, but only in years when your regular tax liability exceeds your tentative AMT. The credit is nonrefundable, meaning you cannot get back more than your regular tax would have been.

The mechanism is slow. A $34,000 AMT bill from an ISO exercise might take five, eight, or more years to fully recover, depending on your income and tax situation each year. Some of it may never come back if you stay in a high-income position where AMT remains your floor. This is one reason people look at early exercise with an 83(b) election when the spread is low: a smaller AMT hit today is easier to recover than a large one later.

What Changes When Your Company Does a Tender Offer

A tender offer is when the company or an outside investor offers to buy shares from employees and existing shareholders. For ISO holders, a tender offer creates a liquidity event: you can finally sell shares that may have been illiquid for years.

The tax treatment of a sale depends on whether you have met the ISO holding periods. If you sell after holding the shares for more than one year from exercise and more than two years from grant, the gain is long-term capital gain, taxed at federal rates up to 20% plus the 3.8% net investment income tax if your modified adjusted gross income exceeds $200,000 (single) or $250,000 (married filing jointly). California taxes capital gains as ordinary income, so the state will take up to 13.3% on top.

If you sell before meeting those holding periods, the sale is a disqualifying disposition. The bargain element at exercise becomes ordinary income (not AMT income, actual ordinary income on your return), and any additional gain beyond the exercise-date value is capital gain. The AMT you paid in the exercise year becomes a credit you can start recovering.

That is the mechanics. The planning question is whether a tender offer presents an opportunity to diversify your concentrated position. Many employees at private AI and tech companies hold most of their net worth in a single illiquid stock. Planning the tax side before the offer closes is the difference between a planned exit and a surprise bill.

For companies whose stock qualifies under Section 1202 as qualified small business stock, the tax outcome can be significantly better: a large share of the gain can be excluded, subject to a dollar cap and holding-period rules that the July 2025 tax law expanded for stock issued after July 4, 2025. The company must also have met the QSBS requirements at issuance. Not every private company qualifies, and the rules are specific, but when they apply, the exclusion can eliminate federal capital gains tax on a large portion of the gain.

What to Do Before Year-End

If you hold ISOs and have not yet exercised, here is the order of operations.

First, find your grant documents. Your strike price, the number of shares, the vesting schedule, the grant date, and whether early exercise is permitted are all in there.

Second, get the current 409A valuation. Your company's finance or legal team can provide it. The spread between the strike price and the 409A is the number that determines your AMT exposure.

Third, run the AMT math. A tax professional can model your regular tax and tentative AMT with and without an ISO exercise. The output is not a single number. It is a range of outcomes depending on exercise timing, future 409A changes, and whether the company eventually goes public or stays private.

Fourth, if you early exercise unvested options, file the 83(b) election within 30 days. That window is unforgiving.

Fifth, consider what you do with the proceeds once you have them. Some executives who eventually sell private company stock invest in real estate, where strategies like cost segregation can reduce taxable income from the new property. Others stack multiple approaches. A tax plan that coordinates equity sales, retirement contributions, and entity structure tends to outperform a series of one-off decisions.

If you hold ISOs and have never modeled the AMT impact of an exercise, book a free 15-minute discovery call at (619) 280-2700 or info@RoadmapTax.com. It's the first step toward seeing what an exercise would do to your tax bill before you commit to one.

FAQ

What is the difference between ISOs and RSUs?

Incentive stock options give you the right to buy shares at a set strike price after they vest. RSUs grant you the shares directly at vest with no purchase required. ISOs can qualify for long-term capital gains treatment if you meet holding periods while RSUs are always ordinary income at vest.

Do I owe tax when I exercise incentive stock options?

For regular tax purposes, exercising ISOs and holding the shares triggers no immediate tax. However, the bargain element is an AMT preference item, meaning you may owe alternative minimum tax in the year of exercise even though you sold nothing and received no cash.

What is the 83(b) election deadline?

The 83(b) election must be filed with the IRS within 30 days of early exercising unvested options or receiving restricted stock. The deadline is absolute and the IRS does not grant extensions. Send it by certified mail with return receipt requested and keep a copy with your tax records.

Can I recover AMT paid on an ISO exercise?

Yes. AMT paid because of an ISO exercise generates a minimum tax credit that can offset regular tax in future years when your regular tax exceeds your tentative AMT. Recovery is often slow and may take many years depending on your income.

When should I early exercise my ISOs?

Early exercise has the lowest tax cost when the spread between your strike price and the current 409A valuation is small, minimizing the AMT impact. It requires cash to purchase the shares and carries the risk that the company fails and the stock becomes worthless.

What happens if I sell ISOs in a tender offer before meeting the holding periods?

Selling ISOs before meeting the one-year-from-exercise and two-years-from-grant holding periods creates a disqualifying disposition. The bargain element at exercise becomes ordinary income, and any additional gain is capital gain. AMT you paid in the exercise year becomes recoverable as a credit.

This article is for educational purposes only and does not constitute tax, legal, or investment advice.