What Happens to Your Stock Options and RSUs in an Acquisition?

In an acquisition, each of your stock options and RSUs ends up one of four ways: converted into the buyer’s equity, cashed out, accelerated, or canceled. Your company’s equity plan sets which of those are allowed, the merger agreement picks among them, and the tax follows the outcome rather than the label on your grant.

• What surprises people: a cashed-out ISO is taxed as wages, an underwater option can disappear for nothing, and private-company RSUs can pile a year of income into the closing month.
• What to do first: get the notice that describes how each of your grants is treated, then project the whole year’s tax before closing, not after.

What happens to stock options when a company is acquired?

The buyer has four tools, and a single deal often uses all of them on different grants. A typical pattern is to cash out vested awards, convert unvested ones into the buyer’s equity so employees keep a reason to stay, and cancel anything underwater.

The option and RSU rows are compensation, which the IRS taxes like salary (IRS Publication 525). Shares you already own are investments, and selling them produces capital gain or loss. That split runs through every section below. For the basics of the two option types, see ISO vs. NSO.

Who decides what happens to your equity?

Two documents decide, and your offer letter is neither of them. The offer letter told you how many options you would get. The equity incentive plan, the document the board adopted to grant every award, has a section on a “corporate transaction” or “change in control” that lists what the board may do with outstanding awards in a sale. The merger agreement then chooses, award type by award type, within that list. Your individual award agreement, or an executive’s employment agreement, can add rights on top, most often acceleration.

In a private deal the merger agreement is rarely shared with employees. What you get instead is a notice or information statement summarizing the treatment, usually a few weeks before closing. Ask for the plan document too, and read three things in it: whether the board can cancel awards the buyer doesn’t assume, whether unassumed awards accelerate, and how long you would have to exercise converted options if you are let go.

Can your stock options be canceled for nothing?

Yes, if they are underwater. An option is underwater when its strike price is at or above the deal price per share, so there is no spread to pay. Merger agreements usually dispose of these options in a single sentence. Vimeo’s 2025 agreement to be acquired at $7.85 a share is typical: “Any Company Option with an exercise price that is equal to or greater than the Merger Consideration will be cancelled for no consideration” (Vimeo Form 8-K).

This hits people who joined late or took refresh grants after a high-priced funding round. If the company sells for less than the valuation behind your grant, those options are gone, even when your earlier, cheaper options pay well. Nothing was paid for them, so there is no loss to deduct.

A deal price below the preferred stock’s liquidation preferences can do the same thing to common stock you own. Investors with preferences are paid back first, and common holders split what remains, which can be little or nothing even in a sale that makes headlines.

How is a stock option cash-out taxed?

As wages, even when the options are ISOs. The favorable ISO rules in 26 U.S.C. § 421(a) apply only “if a share of stock is transferred” to you when you exercise. In a cash-out you never exercise and never receive a share: the company cancels the option and pays you the spread. That payment is compensation for regular tax, and because the Social Security and Medicare exclusion in § 3121(a)(22) covers only the transfer of ISO stock and later dispositions of it, the cash-out is also subject to payroll taxes.

For 2026, that means ordinary income tax plus 6.2% Social Security on wages up to $184,500, 1.45% Medicare on all of it, and another 0.9% Medicare above $200,000 (IRS Publication 15). Someone whose salary has already passed the Social Security wage base pays only the Medicare portions on the payout.

Three consequences people find late:

• No long-term capital gain. Years of holding vested options count for nothing. Only shares you held count toward a holding period.
• No QSBS. The qualified small business stock exclusion applies to gain on stock. An option cashed out at closing was never stock.
• Exercising first changes the payroll tax, not the income tax. If the company lets you exercise vested ISOs before closing and your shares are then bought in the deal, the sale is a disqualifying disposition. The spread is still ordinary income, but it owes no Social Security or Medicare. You need cash for the strike, and for someone already past the Social Security wage base the saving is 1.45% to 2.35% of the spread.

If you already exercised ISOs and paid alternative minimum tax in an earlier year, the sale year is often when that minimum tax credit starts coming back. The AMT guide for ISOs covers the credit.

Do converted ISOs stay ISOs?

Only if the conversion meets the substitution rules in Treasury Regulation § 1.424-1(a). In short, the new option cannot have a bigger spread than the old one, its strike-to-value ratio cannot be more favorable, it must keep the old option’s terms, and it cannot add benefits you didn’t have. A conversion that breaks those rules is treated as a new grant, which can cost the options their ISO status.

Buyers meet the rules with an exchange ratio. Hanesbrands’ 2025 merger agreement, for example, multiplies the number of option shares by the ratio and divides the strike price by it, leaving everything else unchanged (Hanesbrands Form 8-K). If you hold 8,000 options at a $2 strike, the deal price is $20, and the buyer’s stock trades at $50, the ratio is 0.4:

Two ISO rules still bite after a clean conversion:

• The $100,000 limit. Under § 422(d), once more than $100,000 of ISO stock, valued at the grant date, first becomes exercisable in a single year, the excess is treated as NSOs. Acceleration moves years of vesting into one year, so part of an accelerated ISO grant can turn into NSOs.
• The three-month window. ISO status requires exercise within three months of leaving employment, and the statute counts employment with a buyer that assumed the option. If the buyer lets you go a year after closing, that three-month clock starts then, whatever longer window the plan gives you.

What happens to RSUs in an acquisition?

That depends on whether your company is public or private.

Public-company RSUs usually convert into the buyer’s RSUs using the same exchange ratio, and keep vesting. Unvested units often keep your old vesting dates, but some buyers reset part of the schedule or swap it for a new retention grant on a fresh clock, so check the dates in your conversion notice rather than assuming your calendar carried over. Nothing is taxed until each new unit vests, when it becomes wages like any RSU (RSU tax withholding explains how).

Private-company RSUs are where the real surprise sits. Private companies commonly grant RSUs that vest only when two conditions are met: a time-based schedule and a liquidity event, usually defined as an IPO or an acquisition. You may have met the time condition years ago, but nothing was taxed because the liquidity condition was not met. At closing it is, and every unit that has met its time condition settles at once.

“Double trigger” means two different things in a deal, and people mix them up. For private RSUs, it means time vesting plus a liquidity event, and the acquisition fires the second trigger for everyone. For acceleration, it means the acquisition plus losing your job, covered next. The first kind pays out at closing; the second kind may never pay out at all. Use the RSU Tax Calculator to compare the withholding on a settlement like this with what you will owe.

What is single-trigger vs double-trigger acceleration?

Acceleration means unvested awards vest early. Single-trigger acceleration happens on the acquisition alone. Buyers dislike it because it pays out the retention they were buying, so it tends to appear in founder and executive agreements rather than ordinary grants, and sometimes covers only part of the unvested balance.

Double-trigger acceleration needs the acquisition plus a qualifying termination, usually within a window such as 3 to 12 months after closing. A qualifying termination is typically being let go without “cause,” or resigning for “good reason,” which agreements usually define as a material pay cut, a material reduction in duties, or a forced relocation beyond a set distance. Read those definitions in your own agreement. Quitting because you dislike the new job is not good reason, and if the buyer keeps you on through the window, nothing accelerates.

Accelerated RSUs and accelerated options that are cashed out are wages in the year they pay. Accelerated ISOs can also run into the $100,000 limit above.

How are earnouts and escrow holdbacks taxed?

Many acquisitions pay part of the price later. An escrow or holdback keeps a slice of the price, often for a year or more, to cover the buyer’s claims if the company’s promises in the deal turn out to be wrong. An earnout pays more if the business hits targets after closing. Either way, part of your payout may arrive in a later tax year, or never.

How that later money is taxed depends on what you held:

• Options and RSUs. Your share of escrow or an earnout is wages when it is paid. The 409A rules let companies pay deal-related compensation on the same schedule as shareholders, as long as it is paid within five years of closing (Treasury Regulation § 1.409A-3(i)(5)(iv)). If the money is never released, you never owe tax on it.
• Shares of a private company. Deferred payments for shares you sell are usually reported on the installment method, so you report the gain as payments arrive (IRS Publication 537). An earnout makes this a contingent payment sale, with its own rules for spreading basis. Whether escrowed money counts as received at closing depends on how the escrow is set up: Publication 537 treats an escrow that substantially restricts your right to the money differently from one that does not.

Plan your cash around the amount paid at closing, and treat the rest as a possible later payment with its own tax bill.

Does the golden parachute tax apply to you?

It applies only to “disqualified individuals” whose deal-related pay is large relative to their history. Under § 280G, that means officers, holders of more than 1% of the company’s stock, and members of the highest-paid 1% of employees (capped at 250 people). Your base amount is your average W-2 compensation from the company over the last five years.

If payments contingent on the deal, including part of the value of any accelerated vesting, reach three times your base amount, everything above one times the base becomes an excess parachute payment. You owe a 20% excise tax on it under § 4999, on top of income tax, and the company loses its deduction.

That cliff is why executive agreements often include a “best net” clause that trims payments to just under the threshold when that leaves you better off. A private company can avoid the tax entirely with a vote of more than 75% of its shareholders after full disclosure, but the regulations require the vote to decide whether you actually get the payments, so the executive waives them first and gets them back only if the vote passes (Treasury Regulation § 1.280G-1, Q&A-7).

What happens to shares you already own?

Shares you already own, from exercised options, vested RSUs, or founder stock, are bought like any shareholder’s. In a cash deal that is a sale. The gain is long-term if you held the shares more than a year. Shares from ISOs also need more than two years from grant and one year from exercise, or the sale is a disqualifying disposition and part of the gain becomes ordinary income. The guide to selling company stock covers basis and holding periods.

This is where QSBS can matter most. If your shares qualify under § 1202 and you acquired them on or before July 4, 2025, held them more than five years, and stay within the greater of $10 million or 10 times your basis, the federal gain can be fully excluded. Shares acquired after July 4, 2025 can get 50%, 75%, or 100% after three, four, or five years, with a $15 million cap. Two deal-specific rules apply:

• A stock-for-stock deal can carry QSBS status into the buyer’s shares, but if the buyer is not itself a qualified small business, the exclusion is limited to the gain built in at the time of the exchange (§ 1202(h)(4)). Growth after closing is taxed normally.
• A cash deal before you reach the holding period does not have to forfeit the benefit. A § 1045 rollover defers the gain on QSBS held more than six months if you buy other QSBS within 60 days.

If an 83(b) election started your holding period on early-exercised shares, the deal is when that choice pays off.

Worked example: one employee, five outcomes

Maya is single, earns a $200,000 salary, and lives in a state with no income tax. Her startup is bought in November 2026 for $20 a share in cash, with $2 a share (10%) held in a 12-month escrow. Vested awards are cashed out, unvested awards convert into the buyer’s equity at a 0.4 ratio (the buyer trades at $50), and underwater options are canceled.

Her 2026 wages are $736,000: salary plus $536,000 of deal compensation. With the $16,100 standard deduction, her federal income tax on those wages comes to about $222,300. The table below shows why withholding falls short.

The payout is taxed at an average of about 34.6%, not 22%. On top of that, payroll withholds Medicare on the deal compensation, 1.45% plus the 0.9% additional tax, about $12,600. The payout owes no Social Security because her salary already passed the $184,500 wage base.

Her 5,000 shares behave differently. She exercised in March 2021 when the strike equaled the share value, so there was no AMT, and by closing she has held the shares more than five years. If the company meets the QSBS tests, the gain is excluded from federal tax. If not, it is long-term capital gain. The canceled NSOs cost her nothing in tax but hurt to lose, and the 3,200 buyer options will be taxed when she exercises them.

In 2027, if the escrow is released, another $64,000 arrives as wages, plus $10,000 for her shares. That second tax year is easy to leave out of the plan.

What should you do before the deal closes?

The window between signing and closing is usually a few weeks to a few months, and most of the useful moves happen inside it:

• Get the treatment for each grant in writing. List every grant with its strike, vested and unvested units, and what the notice says happens to it.
• Read the definitions that move money. “Good reason,” the acceleration window, the post-termination exercise period for converted options, and the escrow and earnout terms.
• Project the year, including the next one. Add the payout to everything else you earn, then set aside the gap between withholding and the projected tax before spending any of it. If you moved states while the grants were vesting, your old state may tax part of the payout, as Multi-State Taxes explains. The liquidity event checklist walks through the reserve, and the Stock Options Calculator helps if you are weighing an exercise before closing.
• Check QSBS before closing. Ask the company whether it has confirmed QSBS eligibility for the shares, and gather your exercise records while the people who have them are still there.

If your company is selling shares to investors without being acquired, the rules are different; see tender offer taxes.

Where Nino fits

Nino pairs AI planning software with a dedicated CPA and Financial Planner team that maps each of your grants against the deal terms, projects the closing year and the escrow year, and sets the tax reserve and estimated payments before the money arrives. Advisor plans start at $3,600 a year and include tax filing; see how Nino plans equity compensation or book a free consultation before the deal closes.