The capital gains tax on unlisted shares runs from 0% to 37% at the federal level, depending on how long you held the stock and your income for the year. Hold the shares more than a year and you get preferential long-term rates of 0%, 15%, or 20%; sell sooner and the profit is taxed like salary. A 3.8% surtax can apply on top, and high earners in high-tax states can end up owing more than 30% all in. One provision can wipe the federal tax out entirely for qualifying startup stock, and a different provision softens the blow if the investment fails.
The One-Year Line That Sets Your Rate
Federal law splits capital gains into short-term and long-term based on holding period. A long-term capital gain is profit from a capital asset held for more than one year.1Office of the Law Revision Counsel. 26 USC 1222 – Definition of Long-Term Capital Gain Sell before the year-and-a-day mark and the entire gain is short-term.
The clock starts the day after you acquire the shares. For private stock, that acquisition date is documented in the stock purchase agreement or the company’s shareholder ledger. Shares received through splits, bonus issues, or vesting may have different acquisition dates than your original block, so track each lot separately. A one-day difference can be the difference between paying 37% and paying 15%.
Short-Term Rates
Short-term gains get no preference. The IRS taxes them as ordinary income at the graduated brackets.2Internal Revenue Service. Topic no. 409, Capital Gains and Losses For 2026, the seven federal rates are 10%, 12%, 22%, 24%, 32%, 35%, and 37%. The gain stacks on top of your other income, which can push part of it into a higher bracket than you’re used to seeing on your W-2.
If the one-year mark is close, the math almost always favors waiting. A high earner who flips private shares inside a year can lose more than a third of the profit to federal tax alone, before the state takes its share.
Long-Term Rates
Hold more than a year and the gain qualifies for 0%, 15%, or 20%, depending on your taxable income and filing status.2Internal Revenue Service. Topic no. 409, Capital Gains and Losses For 2026, the thresholds are:
- 0% rate: taxable income up to $49,450 (single), $98,900 (married filing jointly), or $66,200 (head of household).
- 15% rate: taxable income from $49,451 to $545,500 (single), $98,901 to $613,700 (married filing jointly), or $66,201 to $579,600 (head of household).
- 20% rate: taxable income above those upper limits.
Most people selling meaningful private company stakes land in the 15% or 20% bracket. The 0% rate mainly helps someone with modest other income who sells a small block at a gain.
The 3.8% Net Investment Income Tax
A separate 3.8% surtax applies to net investment income when your modified adjusted gross income clears a statutory threshold.3Office of the Law Revision Counsel. 26 USC 1411 – Imposition of Tax Those thresholds have not been adjusted for inflation since the tax began in 2013: $200,000 for single and head of household, $250,000 for joint filers, and $125,000 for married filing separately.
The surtax applies to the lesser of your net investment income or the amount your MAGI exceeds the threshold.4Internal Revenue Service. Net Investment Income Tax Capital gains from selling unlisted shares count as investment income. A single filer with $300,000 MAGI and $150,000 of it from a stock sale would owe 3.8% on $100,000 (the excess over $200,000), or $3,800. Combined with a 20% long-term rate, the effective federal rate reaches 23.8%.
Calculating the Gain
The formula is sale price minus cost basis minus selling expenses. Each element needs documentation when the shares aren’t publicly traded.
Sale price is the total consideration from the buyer, whether cash, property, or a combination, as set out in the sale agreement. Cost basis is your original investment in the shares, including the purchase price plus acquisition costs such as legal fees or commissions.5Internal Revenue Service. 2025 Instructions for Form 8949 If you got the shares by exercising stock options, your basis depends on the option type and what you paid at exercise. Selling expenses (legal fees, transfer agent costs, commissions) reduce the taxable gain, and private sales often carry meaningful legal costs for drafting agreements and handling compliance.
Inherited Shares
Shares you inherit take a basis equal to their fair market value on the date the previous owner died, not what that owner originally paid.6Office of the Law Revision Counsel. 26 USC 1014 – Basis of Property Acquired From a Decedent This stepped-up basis can slash the tax bill. Inherit stock worth $500,000 at the date of death, sell later for $550,000, and you owe tax on $50,000, no matter what the decedent paid decades earlier. Getting an accurate date-of-death valuation matters, and for private shares that usually means a formal appraisal.
Gifted Shares
Shares received as a gift carry the donor’s basis forward.7Office of the Law Revision Counsel. 26 USC 1015 – Basis of Property Acquired by Gifts and Transfers in Trust If your aunt paid $10,000 for shares and gave them to you when they were worth $200,000, your basis for calculating a later gain is still $10,000. If the fair market value at the time of the gift was lower than the donor’s basis, a special rule kicks in for losses: your basis for calculating a loss is the lower gift-date value, which stops donors from shifting unrealized losses to the recipient.
Valuing Shares With No Market Price
The practical challenge is figuring out what unlisted shares are worth. There’s no ticker to check. The IRS expects fair market value, defined as the price a willing buyer and willing seller would agree on, both with reasonable knowledge of the facts.
Professional appraisers typically use one of three approaches: an income approach that discounts projected future cash flows to present value; a market approach that compares the company to publicly traded peers or recent private deals using multiples like EV/EBITDA; and an asset approach that nets the fair market value of assets against liabilities. Appraisers commonly apply discounts for lack of marketability and lack of control when the interest is a minority stake, because a small holder can’t force a sale or set direction. Those discounts can reduce taxable value by 20% to 40% in some cases, which is why a qualified appraisal is worth having. If the IRS disputes your valuation and you can’t back it up, additional tax and penalties follow.
Section 1202: The Exclusion That Can Zero Out the Tax
Section 1202 lets non-corporate taxpayers exclude some or all of the gain from selling qualified small business stock (QSBS), potentially cutting the federal capital gains tax to zero.8Office of the Law Revision Counsel. 26 USC 1202 – Partial Exclusion for Gain From Certain Small Business Stock The stock has to meet several tests:
- The issuer must be a domestic C corporation. S corporations and partnerships don’t qualify, though an LLC taxed as a C corporation may.
- You must have acquired the stock at original issuance from the company, in exchange for money, property (other than stock), or services. Buying on the secondary market from another shareholder doesn’t count.
- For stock acquired after July 4, 2025, the corporation’s aggregate gross assets could not have exceeded $75 million at issuance. For stock acquired on or before that date, the ceiling was $50 million.
- During substantially all of your holding period, at least 80% of the company’s assets by value must be used in a qualified active trade or business. Health, law, accounting, financial services, consulting, and performing arts are among the excluded fields.
For stock acquired after July 4, 2025, the exclusion follows a tiered holding schedule: 50% at three years, 75% at four years, and 100% at five or more years. The per-issuer cap on excluded gain is the greater of $15 million or ten times your adjusted basis in the stock, and the $15 million figure starts adjusting for inflation in 2027. For stock acquired on or before July 4, 2025, the cap is $10 million and the full exclusion requires a five-year hold.
A founder who put $100,000 into a qualifying startup, held five years, and sold for $5 million could exclude the entire $4.9 million gain from federal income tax. That’s why tax advisors push founders to confirm QSBS eligibility early.
Section 1244: When the Investment Fails
A loss on unlisted shares is normally a capital loss, which offsets capital gains and then only $3,000 per year of ordinary income, with the rest carried forward. Section 1244 provides an exception. If the stock qualifies, you can treat the loss as ordinary rather than capital, up to $50,000 per year for single filers or $100,000 for joint filers.9Office of the Law Revision Counsel. 26 USC 1244 – Losses on Small Business Stock Ordinary treatment lets you deduct the full amount against wages, business income, and other ordinary income in the year of the loss, with no $3,000 cap. Anything above the Section 1244 annual limit reverts to capital loss treatment.
The stock has to have been issued by a domestic small business corporation, and you must have acquired it directly from the company. Keep the paperwork proving original issuance, because the IRS can challenge the characterization.
Spreading the Tax Over Years With an Installment Sale
Selling a large block in a single year can shove you into the top brackets. Section 453’s installment method lets you spread the gain over several years when the buyer pays over time.10Office of the Law Revision Counsel. 26 USC 453 – Installment Method You recognize gain proportionally as each payment comes in.
The method applies automatically whenever at least one payment lands after the close of the tax year. The statute bars installment reporting for stock traded on an established securities market, but unlisted shares aren’t traded on one and so qualify. Installment sales are reported on Form 6252.
Reporting the Sale
Private stock sales take more manual work than brokerage sales. When you sell publicly traded shares, the broker sends you and the IRS a Form 1099-B. With unlisted shares, you’ll rarely get one, which puts the reporting on you.
Individual capital transactions go on Form 8949. Without a 1099-B, check Box C for short-term transactions or Box F for long-term transactions.5Internal Revenue Service. 2025 Instructions for Form 8949 Enter the description of the shares, acquisition date, sale date, proceeds, and cost basis. Subtotals from Form 8949 carry to Schedule D of Form 1040, where the overall gain or loss is tallied.11Internal Revenue Service. About Schedule D (Form 1040), Capital Gains and Losses
Hold onto your stock purchase agreement, the sale agreement, receipts for selling expenses, and your valuation documentation. The IRS won’t have a 1099-B to match against your return, but large private-stock gains draw audit attention, especially when the reported basis looks high next to the sale price.
Estimated Tax Payments
Nobody withholds tax on a private stock sale, so you generally need to make estimated tax payments if you expect to owe $1,000 or more for the year after withholding and refundable credits.12Internal Revenue Service. Estimated Tax Quarterly due dates are April 15, June 15, September 15, and January 15 of the following year.
If the sale happens mid-year and produces a large gain, you can annualize your income and make a bigger estimated payment for the quarter the sale occurred in, rather than splitting the payments evenly across all four quarters. That means completing the Annualized Estimated Tax Worksheet in IRS Publication 505 and filing Form 2210 with Schedule AI. If you also have W-2 wages, another option is bumping up paycheck withholding for the rest of the year.
Payments run through the Electronic Federal Tax Payment System (EFTPS), IRS Direct Pay, or your IRS Online Account.13Internal Revenue Service. EFTPS: The Electronic Federal Tax Payment System Missing payments or paying too little triggers an underpayment penalty that acts like interest on the shortfall.14Internal Revenue Service. Underpayment of Estimated Tax by Individuals Penalty
State Tax
Federal is only part of the bill. Most states tax capital gains as ordinary income, at rates that run from around 2% to over 13% depending on the state and your income level. A handful of states impose no income tax at all. In a high-tax state, the combined federal-plus-state rate on a long-term gain can easily top 30% for high earners. Check your state’s rules before treating the federal number as the whole picture.
Penalties for Underreporting
Getting the numbers wrong can be expensive. The IRS applies a 20% accuracy-related penalty on underpayments caused by negligence or a substantial understatement of income.15Internal Revenue Service. Accuracy-Related Penalty A substantial understatement means the tax you reported was off by the greater of 10% of the correct tax or $5,000. Intentional fraud can bring criminal penalties.
The most common mistake with unlisted shares isn’t deliberate evasion. It’s simply not reporting the sale because no 1099-B arrived. The omission may not surface right away, but if it comes up during an audit or through matching with the buyer’s return, you’ll owe the tax plus penalties and interest going back to the year of the sale. Report every sale, even when the paperwork feels heavy.