Founders, startup employees, and early investors often hear a lot of tax jargon around QSBS, 83(b), stock options, and capital gains. The hard part is knowing which rule applies to your equity, when it applies, and what to file on your 2025 return filed in 2026. For most calendar-year taxpayers, the 2025 return was due April 15, 2026, and an extension generally moved the filing deadline to October 15, 2026. The 83(b) election is different: it is due within 30 days after the property is transferred, and that deadline does not wait for tax season.
Quick takeaways
- QSBS can exclude some or all gain on qualifying startup stock, but only if the stock is in a domestic C corporation and the company meets the section 1202 rules. For stock issued after July 4, 2025, the IRS instructions use a $75 million gross-assets limit; for stock issued on or before July 4, 2025, the limit is $50 million.
- The QSBS exclusion is still capped per issuer. For 2025 returns, the limit is generally the greater of $10 million or 10 times your basis, with a $5 million cap for married individuals filing separately.
- Founder restricted stock often turns on the 83(b) election. The IRS says you can file Form 15620 or a written statement, but it must be filed within 30 days after transfer. You cannot use 83(b) for stock options.
- Startup employees usually deal with ISOs, ESPPs, or nonstatutory stock options. Each has different timing rules, and ISO exercises can create AMT even when regular tax is not due.
- For a 2025 sale of startup stock, the core reporting forms are usually Form 8949 and Schedule D (Form 1040). QSBS exclusions use code Q on Form 8949; QSBS rollover elections use code R.
Who this applies to
This article applies to individual taxpayers who own startup equity directly: founders, employees, contractors, and investors. It is federal-only. The answer changes depending on whether you hold actual C corporation stock, a restricted stock award, an option, or an interest in an LLC taxed as a partnership or disregarded entity.
Introduction
Startup equity is not one tax rule. It is several rules that can overlap. A founder may get restricted stock and need an 83(b) election. An employee may get an ISO or NSO. An early investor may later sell stock that qualifies for the QSBS exclusion. The wrong move at the wrong time can shift income from capital gain to ordinary income, or create an AMT surprise on an otherwise successful exit.
For 2025 tax returns filed in 2026, the key question is not just “Did you sell startup stock?” It is “What kind of equity did you own, how did you get it, how long did you hold it, and did you file the right election or forms on time?”
What counts as startup equity for tax purposes?
For tax purposes, startup equity can mean several different things:
- Founder stock — usually actual shares issued early in the company’s life, sometimes subject to vesting.
- Restricted stock — stock that is transferred now but is still subject to forfeiture or vesting conditions.
- Stock options — the right to buy stock later at a set price.
- Employee stock purchase plan shares — stock bought under an ESPP.
- Actual C corporation stock — the only kind of equity that can potentially be QSBS.
Myth vs. fact
Myth: Any startup equity is QSBS. Fact: QSBS is limited to stock in a C corporation that meets the section 1202 rules. Options, LLC interests, and many other equity rights are not QSBS by themselves.
QSBS basics: who qualifies and what changed for 2025
QSBS means qualified small business stock. The IRS says the stock must generally be:
- Stock in a C corporation.
- Originally issued after August 10, 1993.
- Issued when the corporation was a qualified small business.
- Acquired at original issue, directly or through an underwriter, in exchange for money, other property, or services.
- Held while the corporation met the active-business rules and did not fall into an excluded business category.
The 2025 IRS instructions also reflect an important threshold change. For stock issued after July 4, 2025, a qualified small business is a domestic C corporation with total gross assets of $75 million or less. For stock issued on or before July 4, 2025, the threshold is $50 million or less. That date matters if your startup issued shares around the middle of 2025.
Not every business qualifies. The IRS excludes certain service businesses and other categories, including businesses in fields such as health, law, accounting, consulting, athletics, financial services, brokerage services, investing, and investment management, along with certain reputation-based businesses.
If your startup is an LLC, entity classification matters. The IRS says a domestic LLC with at least two members is generally treated as a partnership unless it elects corporate treatment. Because QSBS is stock in a C corporation, you need to confirm the company’s federal tax classification before assuming the shares are QSBS-eligible. That is an entity-classification issue, not a QSBS shortcut.
How big is the QSBS exclusion?
For stock that qualifies, the exclusion can be:
- Up to 50% for stock acquired before February 17, 2009.
- Up to 75% for stock acquired between February 17, 2009, and September 27, 2010.
- Up to 100% for stock acquired after September 27, 2010.
There is also a per-issuer cap. The 2025 Publication 550 says the eligible gain is limited to the greater of $10 million or 10 times your basis, minus prior excluded gain from the same issuer. The limit is $5 million for married individuals filing separately.
Founder stock and the 83(b) election
If you received restricted stock as a founder, the 83(b) election is often the first tax decision that matters. Under the IRS rules, if stock is nontransferable or subject to a substantial risk of forfeiture, you generally do not include its value in income until it becomes substantially vested. If you make a timely 83(b) election, you instead choose to include the value in income in the year the stock is transferred.
The election must be filed no later than 30 days after the date the property was transferred. The IRS says you can use Form 15620 or a written statement. The form instructions say the election may be filed by the person performing the services, including an employee or independent contractor.
That deadline is strict. You cannot wait until you file your tax return to decide. The IRS also says you cannot make an 83(b) election for a statutory or nonstatutory stock option.
Two other founder-stock rules are easy to miss:
- If you do not make an 83(b) election, the income is generally recognized when the stock becomes substantially vested, and your holding period begins then.
- Dividends on restricted stock are generally treated as compensation while the stock can still be forfeited. If you do make the 83(b) election, later dividends are treated like normal dividends.
Why founders should care
The 83(b) decision changes the timing of ordinary income. If the company is still early and the stock value is low, that can mean less income is taxed now. If the stock value rises before vesting, waiting can push more of the value into ordinary income later.
Startup employee equity: ISOs, NSOs, and ESPPs
If you are not a founder, your startup equity may be an option rather than actual stock. The IRS separates startup options into two broad buckets: statutory stock options and nonstatutory stock options. Statutory options include incentive stock options (ISOs) and options under an employee stock purchase plan (ESPP). Everything else is generally a nonstatutory stock option.
ISO basics
The IRS says you generally do not include income when an ISO is granted or exercised, but you may have an AMT adjustment in the year of exercise. If you exercise an ISO during 2025, you should receive Form 3921 by January 31, 2026. That form gives the dates and values you need for your records and your return.
When you later sell the stock, you may need to adjust basis, and the IRS specifically says you are responsible for making the appropriate adjustments on Form 8949 if the broker statement is incomplete or wrong.
ESPP basics
If you sold stock acquired under an ESPP in 2025, you should generally receive Form 3922 by January 31, 2026. The IRS says that stock can produce both ordinary income and capital gain, depending on whether you satisfied the holding-period rules.
Nonstatutory option basics
Most startup NSOs are nonstatutory stock options. The IRS says that if the option does not have a readily determinable value, there is generally no taxable event at grant; instead, you include income when you exercise the option, measured as the stock’s fair market value minus the amount you paid. The employer should report the spread on your Form W-2, typically in box 12, code V.
For those shares, your basis is generally the amount you paid plus the amount you included in income, and your holding period begins on the date of exercise.
How to report a 2025 sale on your 2026 return
For most individual taxpayers, the sale of startup stock is reported on Form 8949 and Schedule D (Form 1040). The IRS says to complete Form 8949 first, then complete Schedule D. Form 8949 is also where you reconcile any mismatch between your records and a broker statement.
For a qualified QSBS sale, the IRS says to report the sale on Form 8949, Part II, then enter “Q” in column (f) and the excluded gain as a negative number in column (g). If you are making a QSBS rollover election under section 1045, use “R” instead.
If your stock sale is being paid over time, the installment method may apply. The IRS says that if you sold property and will receive a payment after the tax year of sale, you generally report the sale on Form 6252 unless you elect out. The rollover election for QSBS also has its own timing rule: it must be made by the due date of the return for the year of sale, including extensions, with a limited amended-return window if the original return was timely filed.
What changed this year
Two 2025 changes matter for startup equity:
- The IRS instructions now reflect a $75 million gross-assets limit for QSBS issued after July 4, 2025, while stock issued on or before that date remains under the $50 million limit.
- The IRS now provides Form 15620, Section 83(b) Election, as an official form option for making the 83(b) election. The form and the updated Publication 525 both point taxpayers to the same 30-day filing deadline.
Practical examples
Example 1: Founder restricted stock with an 83(b) election
Simplified illustration. A founder receives 20,000 shares of restricted stock for $0.10 per share, or $2,000 total. The stock’s fair market value on transfer is $0.40 per share, so a timely 83(b) election would include $6,000 of income now [(20,000 × $0.40) − $2,000]. If the founder waits and the shares vest when the stock is worth $8 per share, the ordinary-income amount at vesting could be much larger. The IRS says the election must be filed within 30 days of transfer and cannot be revoked without IRS consent.
Example 2: ISO exercise with AMT exposure
Simplified illustration. An employee exercises 5,000 ISO shares with a $1 strike price when the stock is worth $11. For regular tax, the exercise may not create current income, but the spread can create an AMT adjustment. The IRS says ISO exercise information is reported on Form 3921, and AMT adjustments are figured on Form 6251.
Example 3: QSBS exit with a large gain
Simplified illustration. A founder bought qualifying startup stock for $50,000 and sells it six years later for $12.5 million. Assuming all section 1202 rules are met and the stock was acquired after September 27, 2010, the exclusion can be up to 100%, but the per-issuer cap still matters. The IRS says the allowable exclusion is generally limited to the greater of $10 million or 10 times basis; here, that would be $10 million, so the taxable gain would still be $2.45 million before other tax items.
Quick checklist
- Confirm whether your equity is actual C corporation stock, an option, restricted stock, or an LLC interest.
- If you got restricted stock, decide on the 83(b) election within 30 days and keep proof of filing.
- Save every cap table, grant agreement, vesting schedule, and sale closing statement. You will need them to support basis and holding period.
- Match your forms: 3921 for ISOs, 3922 for ESPPs, W-2 for nonstatutory option spread, and Form 8949/Schedule D for the sale.
- If your exit has deferred payments or a possible QSBS rollover, check Form 6252 and the section 1045 timing rules before filing.
FAQ
Is every founder share QSBS?
No. QSBS requires stock in a domestic C corporation that meets the section 1202 rules. If your startup is an LLC taxed as a partnership or disregarded entity, the answer is different.
Do I need an 83(b) election if I got stock options?
Usually no. The IRS says you cannot make an 83(b) election for a statutory or nonstatutory stock option. The election is for restricted property transferred for services.
What if I miss the 83(b) deadline?
You usually lose the election. The IRS says the statement must be filed within 30 days after the transfer date. That deadline is one of the most time-sensitive startup tax rules.
Can I exclude more than $10 million of QSBS gain?
Usually not from one issuer in one taxpayer’s hands. The IRS limits the exclusion to the greater of $10 million or 10 times basis, reduced by prior excluded gain from the same issuer, and the limit is $5 million for married filing separately.
Does ISO exercise create tax?
Not usually for regular tax at exercise, but it can create AMT. When you later sell the stock, the sale may create capital gain or, if the holding-period rules are not met, some ordinary income treatment.
Do I report QSBS on Schedule D or Form 8949?
Both. The IRS says to use Form 8949 first and then Schedule D. QSBS exclusions use code Q on Form 8949, and rollover elections use code R.
Bottom line
Startup equity can create very different tax results depending on whether you hold QSBS, restricted founder stock, an ISO, an NSO, or an ESPP share. For 2025 returns filed in 2026, the biggest mistakes are missing the 83(b) deadline, assuming all startup stock is QSBS, forgetting the $10 million / 10x basis cap, and using the wrong reporting form. If your equity is tied to vesting, deferred payments, a company conversion, or a possible QSBS exit, this is a good point to slow down and have a CPA, EA, or tax attorney review the facts before you file.
What to do next
- Pull your grant documents, cap table, vesting schedule, and any Form 3921/3922 or W-2 items you received.
- Check whether you filed an 83(b) election within 30 days if you received restricted stock.
- Confirm whether your company is truly a C corporation and whether the shares can qualify for QSBS.
- If you sold stock in 2025, make sure the sale is reported on Form 8949 and Schedule D with the right code and basis adjustment.
- If your exit includes deferred payments or a QSBS rollover, review Form 6252 and section 1045 timing before the return is filed.
Source note: Sources consulted include IRS forms, instructions, publications, official updates, and related guidance.
