Tender Offer Taxes: What Startup Employees Owe

A tender offer is usually taxed as a stock sale, but three facts decide what you owe: who is buying, what kind of shares you are selling, and how long you have held them.

• The cheap case: shares held long enough produce long-term capital gain at 15% or 20%, plus the 3.8% net investment income tax for most sellers.
• The expensive cases: options exercised in order to sell, ISO shares sold too early, and any part of the price treated as pay are taxed at ordinary rates of up to 37%, often with little or nothing withheld.

The window to decide is short. Under the SEC’s Rule 14e-1, a tender offer has to stay open for at least 20 business days, about four weeks, and that is all the time you get to find your grant records and run the numbers. Most of the tax was settled long before the offer arrived, by when you exercised, which grant each share came from, and where you lived while it vested. What follows are the rules that catch employees late, and the numbers on selling NSO shares next to ISO shares held long enough.

What is a tender offer, and who is buying?

A tender offer is an offer to buy shares from many holders at one fixed price during a set window. In a private company it comes in two forms, and the difference matters for tax:

• A company buyback. The company repurchases its own shares, often with cash from a new funding round.
• An investor-led tender. A new or existing investor buys shares directly from employees and early holders, with the company running the process.

Offers usually cap how much each person can sell. Two tax rules below turn on who the buyer is: whether part of the price counts as wages, and whether the sale damages the qualified small business stock (QSBS) status of shares you keep.

How is a tender offer taxed?

It depends on the shares. Each lot you sell is taxed by its own history:

The spread is the difference between what a share was worth when you exercised and the strike price you paid. A gain is long-term once you have held the shares more than a year. For 2026, the 20% rate on long-term gains starts above $545,500 of taxable income for a single filer and $613,700 for a joint return, with 15% below that (Rev. Proc. 2025-32). The net investment income tax adds 3.8% once income passes $200,000 ($250,000 joint).

Can part of the tender price be taxed as wages?

Yes, and it is the rule employees hear about last. The tax code treats compensation for services as income in whatever form it arrives (Section 61), and Treasury regulations treat value a shareholder hands an employee for services as if the company paid it (Treas. Reg. §1.83-6(d)). So when a tender pays more than your shares are worth, the question becomes why the buyer paid extra.

The usual measure of worth is the company’s latest 409A valuation, the independent appraisal of the common stock that the company uses to set option strike prices. Tender prices often sit above it, sometimes at the price investors paid for preferred stock. The premium is most likely to be treated as pay when:

• the company itself is the buyer,
• only employees can sell, or employees get a better price than other holders, or
• the buyer is an insider with a reason to reward the team, not a new investor setting its own price.

When that happens, the premium is taxed like a bonus: ordinary income tax, Social Security and Medicare tax, and withholding, reported on your W-2. The offer documents usually carry a tax section saying how the company plans to treat the payment. Read it before you tender, because it tells you whether part of your proceeds will arrive as wages.

What happens if you sell ISO shares before the holding periods end?

An incentive stock option (ISO) sale gets full capital-gain treatment only if it comes more than two years after the grant date and more than one year after you exercised (Section 422). The later of the two dates controls. A sale before then is a disqualifying disposition, and the spread at exercise becomes ordinary income, or your actual gain if that is smaller. Anything above the exercise-date value is capital gain (California FTB Publication 1004 lays out the split in a table).

Tenders catch people on the exercise date. Say your grant is from March 2024, you exercised in December 2025, and the tender closes in November 2026. The grant is old enough, but the shares have been yours for less than a year, so selling them in this tender is a disqualifying disposition. Waiting until after December 2026 would have qualified, and the tender will not wait.

That income is easy to underpay because the tax code bars withholding on it (Section 421(b)). Your proceeds arrive whole, and the tax shows up in April. The one consolation is that Social Security and Medicare tax don’t apply to it (Section 3121(a)(22)).

If you exercise and sell in the same calendar year, the Form 6251 instructions generally require no alternative minimum tax adjustment for that exercise. Nino’s guide to ISOs and NSOs covers the rest of the ISO rules.

Should you exercise options just to sell them in the tender?

Many tenders let you exercise vested options and sell the shares in one step, with the strike price taken out of the proceeds. It costs no cash up front and carries no risk, but it gives up capital-gain treatment entirely:

• NSOs: the whole spread is wages. Your employer withholds federal income tax at the flat 22% supplemental rate (37% on supplemental wages above $1 million for the year), plus Social Security and Medicare tax (IRS Publication 15).
• ISOs: exercising and selling at once is automatically a disqualifying disposition. The spread is ordinary income with no Social Security or Medicare tax, and nothing withheld.

The worked example below shows what that costs next to shares you exercised years ago.

How much more do NSO shares cost to sell than ISO shares held long enough?

Assume a single filer in 2026 earning a $300,000 salary, with the $16,100 standard deduction and no other income. They sell 10,000 shares in a tender at $30, a price the company treats as fair market value, and the strike price on every grant is $2. Three ways to arrive at the same sale:

• A, NSO exercise-and-sell: NSOs exercised in the tender itself.
• B, ISO exercise-and-sell: ISOs exercised in the tender itself.
• C, ISO shares held long enough: ISOs granted in 2022 and exercised in August 2024, when the 409A value was $8, so the sale clears both holding periods.

How the numbers work:

• Ordinary income. The salary leaves $283,900 of taxable income, already inside the 35% bracket that runs from $256,225 to $640,600 for a single filer in 2026 (Rev. Proc. 2025-32). The $280,000 spread stays inside it, so it costs 35%, or $98,000.
• Payroll tax. The salary already passed the $184,500 Social Security wage base, so only Medicare applies to the NSO spread: 1.45% plus the 0.9% Additional Medicare Tax on wages above $200,000 (IRS Publication 15).
• Long-term gain. Gains stack on top of ordinary income. The first $261,600 fills the 15% bracket up to $545,500 ($39,240), and the last $18,400 is taxed at 20% ($3,680).
• Net investment income tax. Income of $580,000 sits $380,000 over the $200,000 threshold, more than the $280,000 gain, so the whole gain is taxed at 3.8%.
• Withholding. The NSO spread is withheld at 22% ($61,600) plus the Medicare tax ($6,580). The ISO sales have nothing withheld.

Holding ISO shares long enough saves $51,020 against the NSO sale, and $44,440 against exercising the same ISOs in the tender. That saving was paid for earlier: $20,000 of cash in 2024, possible alternative minimum tax (AMT) on the $60,000 spread at exercise, and two years of owning shares that could have become worthless. The stock options calculator estimates that exercise-year cost.

Does a tender offer affect QSBS?

Qualified small business stock can exclude some or all of the gain on stock of a qualifying C corporation from federal tax under Section 1202. A tender interacts with it in three ways.

The clock is probably too short. For shares from options, the holding period starts when you exercise, not when you were granted the options. For restricted stock with an 83(b) election, it generally starts when the shares were transferred to you. Stock acquired on or before July 4, 2025 needs more than five years for any exclusion. The 2025 tax law, the One Big Beautiful Bill Act, added a tiered exclusion for stock acquired after July 4, 2025: 50% after three years, 75% after four and 100% after five. The earliest any post-July 2025 share can reach the first tier is July 2028, so a tender before then gets no exclusion on those shares.

A rollover can rescue the gain. If you held the stock more than six months, a Section 1045 election defers the gain when you buy replacement QSBS within 60 days of the sale.

A company buyback can disqualify the shares you keep. Section 1202(c)(3) contains two redemption rules, with de minimis thresholds in Treas. Reg. §1.1202-2:

• Your own sale. If the company buys more than a de minimis amount of stock from you or a related person (more than $10,000 and more than 2% of your holdings), shares the company issued you in the two years before or after that purchase are not QSBS. Options you exercised in 2025, or plan to exercise in 2027, can lose their status because you sold other shares back in 2026.
• A large buyback. If the company repurchases more than 5% of the total value of its stock (and more than the de minimis amount), stock issued to anyone in the year before or after is not QSBS.

A purchase by an outside investor is not a company redemption. The statute also counts purchases made “directly or indirectly”, though, so a deal the company funds or routes through a third party deserves a closer look. Before you sell to the company, list every exercise in the past two years and every one you plan in the next two. Nino’s QSBS guide covers the company tests and the state exceptions.

Can a tender sale recover AMT you paid on an earlier ISO exercise?

Often, yes. Exercising ISOs and holding the shares adds the spread to your alternative minimum taxable income, and any AMT you pay as a result becomes a minimum tax credit you carry forward on Form 8801. Each year you can use the credit only up to the amount your regular tax exceeds your tentative minimum tax (Section 53(c)).

A tender sale opens that gap. Your AMT basis in the shares includes the spread you were already taxed on, so the AMT gain is smaller than the regular gain, and the difference is a negative adjustment on Form 6251, line 2k. In case C, the AMT gain is $220,000 against a regular gain of $280,000. Regular tax comes to about $111,050 and the tentative minimum tax to about $90,170 (using the 2026 single exemption of $90,100, which phases out above $500,000), leaving room for roughly $20,880 of credit, more than the AMT a $60,000 spread typically produces at the 26% and 28% AMT rates.

The credit is easy to miss. Form 1099-B reports your regular-tax basis, so the AMT basis has to come from your own exercise records and the Form 3921 the company issued for the exercise year. Nino’s guide to avoiding AMT on ISOs covers the exercise side.

Which state taxes your tender proceeds if you moved?

Usually more than one, and the split follows the type of income. California publishes the clearest rules in FTB Publication 1004:

• Capital gain is taxed by the state where you live on the sale date. A former Californian who sells long-held ISO shares in a qualifying sale after moving to Texas owes California nothing on that gain.
• NSO spread and disqualifying-disposition income are wages, and California taxes a nonresident on the share earned there: California workdays between grant and exercise, divided by total workdays in that period. Moving does not erase it, though your new state may give a credit for tax paid to California.
• Moving just before the tender draws scrutiny, because residency turns on where your life actually is, not on a new lease.

Other states use their own sourcing rules, so list every state where you lived or worked between each grant and its sale. Multi-State Taxes covers how a state decides you’ve left and how the credit for tax paid to another state works. The California tax calculator shows that state’s rates, and Nino’s page on moving states covers the move itself.

How do you avoid an underpayment penalty after a tender?

Set the cash aside the day the sale settles, then decide how to pay. The IRS expects tax paid during the year, and a capital gain or ISO sale has nothing withheld. IRS Publication 505 sets the safe harbors: no underpayment penalty if withholding and estimated payments cover the smaller of 90% of this year’s tax or 100% of last year’s, raised to 110% when last year’s AGI was above $150,000.

Three ways to meet them after a tender:

• Pay 110% of last year’s tax. For a household with steady income last year, that can be far less than the tender adds, and the rest is due in April with no penalty. The cash is still due, so it has to be sitting somewhere.
• Raise withholding before December 31. Withholding counts as paid evenly through the year, whenever it actually happened (Section 6654(g)), so a larger W-4 amount in November and December covers earlier quarters too.
• Pay estimated tax on the annualized method. It matches each payment to the quarter the income arrived in, so a November tender can be covered by the fourth payment, due January 15, 2027. You file Form 2210 with Schedule AI to claim it.

Nino’s liquidity event checklist covers the reserve and the records in more detail.

Should you sell in a tender offer?

Tax is one input. A tender is often the only chance to turn private stock into cash before an IPO or acquisition that may be years away, and selling some of a concentrated position can be worth paying more tax. If you give to charity, the extra income also raises how much you can deduct that year, which makes it a natural year to fund a donor-advised fund. When you can choose which lots to sell, start with the cheapest: long-term NSO shares and ISO shares past both holding periods, before exercise-and-sell or disqualifying lots.

Before the window closes, pull together:

• the grant date, exercise date and 409A value at exercise for every lot,
• the latest 409A value next to the tender price, and the tax section of the offer documents,
• every exercise in the past two years and any planned in the next two, if QSBS is in play,
• the states you lived and worked in since each grant, and
• last year’s AGI and total tax, to size the safe harbor.

How Nino helps with a tender offer

Nino’s Advisor plans pair a CPA and a Financial Planner who work from one picture of your grants, exercises and household income. Before the window closes they model which lots to sell, the federal and state tax, and the payment that keeps you inside the safe harbor, then prepare the return the sale lands on. See how Nino handles equity compensation.

Book a free consultation before your tender window closes. Advisor plans start at $3,600 a year with a 30-day money-back guarantee; see plans and pricing.