Why Does Your Broker Report $0 Basis on Vested Shares? (w/Examples) + FAQs

This article reflects federal rules and general state guidance as of June 2026 and covers tax year 2025 (the 2026 filing season). Tax law changes — confirm current figures before you file.

Quick Answer

Your broker reports $0 cost basis on vested shares because the IRS does not require brokers to report the value you already paid tax on at vesting. For tax year 2025, you must add that value back on Form 8949 using code B, or you will pay tax twice on the same income.

When restricted stock units (RSUs) or other equity awards vest, their full value already hits your W-2 as ordinary wages, and you pay income tax on it through payroll. But when you later sell those shares, your broker often prints a cost basis of $0 on Form 1099-B — making it look like the entire sale price is profit, even though you were taxed on most of it months earlier.

This single quirk is one of the most common and expensive filing mistakes in equity compensation, and it hits hardest in tech, biotech, and finance. The income reported on the Form 1099-B from brokers can overstate your gain by tens of thousands of dollars, and if you copy it straight into your return you either overpay the IRS or trigger a mismatch notice. The deadline to fix it is the same as your return: April 15, 2026 for tax year 2025.

💸 Why your broker legally leaves basis blank — and why that is not a broker “error”
🧮 The exact Form 8949 math to recover your real cost basis (with dollar examples)
🏛️ How federal rules differ from state rules, including no-income-tax states
⚠️ The CP2000 notice trap and how to respond if you already filed wrong
🛠️ A step-by-step fix you can copy whether you use TurboTax or a CPA

Which Situation Applies to You?

The right fix depends on where you are in the process. Find your row and jump to the section that fits.

You are filing your 2025 return now and your 1099-B shows $0 basis — go to The Step-by-Step Fix on Form 8949.
You already filed and the IRS sent you a CP2000 notice — go to Already Filed Wrong? Fixing It After the Fact.
You are not sure which equity type you have (RSU, ESPP, ISO, NQSO) — go to Not Just RSUs: Other Equity With Basis Traps.
You sold shares in a state with income tax — go to Federal vs. State: Your Basis Fix Crosses Both.
You have not sold yet but want to avoid this next year — go to Do’s and Don’ts.

This branching matters because one wrong number on the wrong form can cost you a four-figure overpayment, and the cure is different for each path.

What “$0 Basis on Vested Shares” Actually Means

Cost basis is simply what you paid for an asset, and the IRS uses it to measure your gain when you sell. For a normal stock you buy, basis is the purchase price. For vested equity, basis is the value the shares had on the day they vested — because that value was already taxed as your wages.

When your RSUs vest, your employer treats the fair market value (FMV) of the shares that day as ordinary income. That amount lands in Box 1 of your W-2 and is taxed like salary, with federal, state, Social Security, and Medicare withholding, as the IRS explains for restricted stock. Because you were taxed on that FMV, the same FMV becomes your cost basis going forward. You should never be taxed on it again.

The trouble starts at the sale. Your broker sends a Form 1099-B reporting the proceeds, and often lists the cost basis as $0 or leaves it blank and marks the shares “noncovered.” A $0 basis tells the IRS the shares cost you nothing, so your entire sale price looks like a capital gain. If you already paid tax on most of that amount at vesting, reporting it again is textbook double taxation.

Why Your Broker Reports $0 (It Is Not a Mistake)

This is the part that confuses people most: the $0 is usually correct from the broker’s point of view, even though it is wrong for your taxes. Brokers follow a narrow IRS reporting rule, and that rule does not cover the wage income piece of your shares.

Under the cost-basis reporting rules that took effect for stock acquired in 2011 and later, brokers must report basis only for “covered” securities, which generally means shares you bought through the broker. The IRS specifically allows brokers to leave out the compensation income portion of equity-comp shares. So for vested RSUs, the broker reports the proceeds and reports a basis that excludes the wage income — which often shows as $0.

The consequence of misreading this is direct: if you assume the broker is “right” and file the $0, you overstate your gain dollar-for-dollar. A common misconception is that you should call the broker and demand they fix the form — but they will not, because the form is correct under their rules. What you should do: treat the $0 as expected, then supply the real basis yourself on Form 8949 before the April 15, 2026 deadline.

A second misconception is that “noncovered” means you did something wrong. It does not. Noncovered simply means the IRS did not require the broker to track basis for those shares, so the job falls to you.

How to Find Your True Cost Basis

Your real basis is the FMV per share on the vesting date, multiplied by the number of shares that vested. This is the same per-share value your employer used to calculate the W-2 income.

You can pull these numbers from three reliable places. First, your broker’s supplemental statement — a separate document (not the 1099-B itself) that lists the “adjusted cost basis” for each lot. Second, your equity portal (Fidelity NetBenefits, Morgan Stanley at Work / ETRADE, Schwab/Shareworks), which shows the vesting date, share count, and FMV. Third, your year-end pay stub or W-2 detail*, where the RSU income is broken out.

One nuance trips up many filers: shares your employer withheld to cover taxes (“sell-to-cover”) do not change the per-share basis of the shares you keep. Those withheld shares are already reflected in your W-2 withholding, so you only calculate basis on the shares actually delivered to your account.

The Step-by-Step Fix on Form 8949

You fix the $0 basis on Form 8949, Sales of Capital Assets, which feeds into Schedule D. The goal is to keep the IRS’s records matching while reporting your true gain.

Enter the sale as the broker reported it. Use the description, proceeds, and the $0 (or blank) basis from your 1099-B. This keeps your numbers reconcilable with what the IRS already received.
Pick the correct Form 8949 part. Use Part I for short-term lots (held one year or less after vesting) and Part II for long-term lots. RSU shares sold right at vesting are almost always short-term.
Enter your real basis in column (e). This is your vesting-date FMV times shares.
Use code B in column (f). Code B signals the basis reported to the IRS was wrong and you are correcting it.
Enter the adjustment in column (g). This is a negative number equal to the basis you are adding back, which reduces the overstated gain.
Carry the corrected totals to Schedule D. Your final gain or loss should now reflect only the change in price after vesting.

If you use tax software, look for the prompt that says the shares are “employee stock” or “RSU” and asks for the “corrected cost basis.” Entering the right number there makes the software apply code B automatically. The deadline to file with the correction is April 15, 2026 for tax year 2025; an extension to October 15, 2026 extends the filing date but not the payment date.

Worked Numeric Example: The $0 Basis Trap in Dollars

Numbers make this concrete, so here is the full math you can copy. Assume a clean, single-lot RSU sale.

1,000 RSUs vest on March 1, 2025
FMV at vesting: $100 per share, so $100,000 is added to your W-2 and taxed as wages
You sell all 1,000 shares on June 15, 2025 for $105 per share, so proceeds are $105,000
Your 1099-B shows proceeds of $105,000 and cost basis of $0

If you file the $0 as-is, the IRS sees a $105,000 short-term gain. At a 35% marginal rate that is about $36,750 of federal tax — on top of the income tax you already paid on the $100,000 at vesting.

Now the correct version. Your true basis is 1,000 × $100 = $100,000. Your real gain is $105,000 − $100,000 = $5,000. At 35% that is $1,750 of federal tax. The $0-basis mistake would have cost you roughly $35,000 extra on a single sale.

Form 8949 Side-by-Side

Here is exactly what the broker shows versus what you should report.

What your broker’s 1099-B shows	What you actually report on Form 8949
Description: 1,000 ABC shares	Description: 1,000 ABC shares
Proceeds: $105,000	Proceeds: $105,000
Cost basis: $0	Cost basis (col. e): $100,000
Reported gain: $105,000	Adjustment (col. g): −$100,000, code B
—	Corrected gain: $5,000

Three Common Scenarios

Most filers fall into one of these three patterns. Each shows the trigger and the result if handled correctly.

Scenario 1 — Sell-to-cover at vesting, hold the rest.

Your situation	Tax result
500 shares vest at $80 FMV; 185 auto-sold to cover taxes; you keep 315	The 185 covered shares have basis $80 each, near-zero gain; the 315 you keep carry $80 basis for a future sale

Scenario 2 — Same-day sale of all vested shares.

Your situation	Tax result
1,000 shares vest and sell the same day at $100 FMV	Basis $100,000, proceeds ~$100,000, gain near $0; without the fix the 1099-B shows a phantom $100,000 gain

Scenario 3 — Hold over a year, then sell higher.

Your situation	Tax result
1,000 shares vest at $100, sold 14 months later at $140	Basis $100,000, proceeds $140,000, $40,000 long-term gain taxed at lower rates; the post-vesting growth is the only new tax

Named Examples

Priya, a software engineer at a public tech firm. Priya’s 800 RSUs vested at $150 in 2025, putting $120,000 on her W-2. She sold all 800 a week later at $152 for $121,600. Her 1099-B showed $0 basis and a $121,600 gain. By entering $120,000 in column (e) with code B, her real gain dropped to $1,600, saving her roughly $42,000 in unnecessary federal tax.

Marcus, a biotech analyst who held his shares. Marcus let his 2,000 RSUs ride for 18 months after vesting at $40 ($80,000 W-2 income). He sold at $55 for $110,000. The broker reported $0 basis. After correcting basis to $80,000, his long-term gain was $30,000, taxed at the 15% capital-gains rate instead of being inflated to $110,000.

Dana, who already filed without the fix. Dana copied her $0-basis 1099-B straight into TurboTax in early 2025 and overpaid. She caught it in May, filed Form 1040-X with a corrected Form 8949, and recovered about $18,000.

Not Just RSUs: Other Equity With Basis Traps

RSUs are the most common $0-basis case, but the same trap appears with other equity compensation, each with its own twist. The fix is similar — add back the income already taxed — but the source of that income differs.

Employee Stock Purchase Plans (ESPP). With a qualifying ESPP, the discount you received is taxed as ordinary income and belongs in your basis, yet brokers often report only what you paid out of pocket. Per the IRS rules on employee stock purchase plans, you add the discount income (from your W-2 or Form 3922) to basis to avoid double tax.

Nonqualified stock options (NQSOs). When you exercise an NQSO, the spread between the exercise price and the FMV is wage income on your W-2. Your true basis is the FMV at exercise, but the 1099-B often shows only the exercise price, understating basis by the spread.

Incentive stock options (ISOs). ISOs are trickier because of the alternative minimum tax (AMT). For a regular-tax sale, basis is what you paid; but if you triggered AMT at exercise, you may have a separate, higher AMT basis. The IRS guidance on ISOs and Form 6251 govern this, and it often warrants a professional.

Federal vs. State: Your Basis Fix Crosses Both

The federal fix on Form 8949 is only half the picture, because most states start from your federal numbers. If you correct basis federally, the corrected gain usually flows to your state return automatically — but the details vary, so never assume.

States with an income tax (like California, New York, and Massachusetts) generally tax the same capital gain you report federally, just at their own rates. California, home to many RSU recipients, taxes capital gains as ordinary income with no special lower rate, so fixing your federal basis directly lowers your California tax too. New York behaves similarly for residents.

Here is the federal-versus-state contrast at a glance.

Federal treatment	State treatment
Basis = vesting FMV; correct on Form 8949 with code B	Most income-tax states start from federal gain, so the fix carries over
Capital gains taxed at 0/15/20% long-term federal rates	States like California tax gains as ordinary income, with no lower long-term rate
Form 8949 + Schedule D required	No-tax states (TX, FL, WA, NV, etc.) impose no income tax on the gain at all

If you live in a no-income-tax state such as Texas, Florida, Washington, Nevada, South Dakota, Wyoming, Alaska, or Tennessee, the state side is simple: there is no state income tax on your gain, so only the federal fix matters. Washington is the one to watch — it imposes a separate capital-gains excise tax on large long-term gains, so high earners there should check the Washington capital gains tax page. If you changed states or worked in multiple states during the vesting period, multi-state allocation gets complex and is a strong signal to hire a pro.

Already Filed Wrong? Fixing It After the Fact

If you already filed and copied the $0 basis, you have two likely situations, and both are fixable. The key is acting before penalties and interest pile up.

If you overpaid but the IRS has not contacted you, file an amended return on Form 1040-X with a corrected Form 8949 attached. You generally have three years from the original filing date to claim the refund, so a 2025 return filed in 2026 can be amended through about April 2029. The refund typically takes 8–12 weeks or longer.

If the IRS sent you a CP2000 notice, do not panic and do not just pay it. A CP2000 notice from the IRS is an automated proposal, not a bill, generated when the income on your return does not match third-party forms. Respond by the deadline on the notice (usually 30 days) with your corrected Form 8949 showing the real basis and a short explanation. If you ignore it, the proposed tax becomes a real assessment with penalties and interest.

The cost of help varies: a DIY amendment is free beyond your software fee, while a CPA typically charges $300–$800 to amend a return or answer a CP2000, money well spent if the numbers are large or span multiple states.

Mistakes to Avoid

Filing the $0 basis as-is. This overstates your gain and can cost tens of thousands in tax you do not owe.
Calling your broker to “fix” the 1099-B. They will not change it, and you will lose time you need before the deadline.
Forgetting the supplemental statement. Skipping it means you never see the real basis, so you guess or default to $0.
Counting sell-to-cover shares twice. Withheld shares are already in your W-2 withholding; double-counting them inflates basis incorrectly.
Using the wrong holding period. Misclassifying a short-term lot as long-term (or vice versa) changes your rate and can trigger a notice.
Ignoring a CP2000 notice. Silence turns a fixable proposal into an enforced assessment with penalties.
Assuming your CPA caught it. Preparers often enter 1099-B numbers verbatim unless you hand them the vesting FMV.
Mixing up lots. Selling without specific-lot identification can lock in a larger gain than necessary across multiple vesting years.

Do’s and Don’ts

Do:

Do pull your supplemental 1099-B statement every year, because it holds the real basis the main form omits.
Do enter your true basis with code B on Form 8949, since that is the IRS-blessed way to correct it.
Do save your vesting confirmations and pay stubs, because they prove your basis if questioned.
Do reconcile the W-2 RSU income to your equity portal, so the numbers tie out before you file.
Do consider specific-lot identification when selling part of your shares, because it can cut your taxable gain.

Don’t:

Don’t trust the 1099-B gain figure, because it is frequently overstated for vested shares.
Don’t double-count withheld shares, since that creates a basis error in the other direction.
Don’t wait until April 14 to hunt for basis data, because portals and supplements take time to find.
Don’t amend without the corrected Form 8949, or the IRS cannot see why your number changed.
Don’t guess your FMV, because an invented figure is the kind of error that draws an audit.

Pros and Cons of Correcting Basis Yourself (DIY)

Pros:

It is free, because you only pay your existing software cost.
It is fast for a single clean lot, since the math is one subtraction.
You control accuracy, because you are the one with the vesting data.
It builds a repeatable system you can reuse every vesting year.
It avoids a CP2000 when done correctly, sparing you future hassle.

Cons:

It is error-prone with many lots, because each vesting date has its own basis.
AMT and ISO cases get complex, which can exceed DIY comfort.
Multi-state allocation is hard, since each state may want its own split.
Software can mis-handle code B, so a missed prompt reintroduces the error.
Mistakes compound, because one wrong basis can cascade across Schedule D and the state return.

What to Do Next

Pull your 1099-B and its supplemental statement from your broker’s portal today.
Find the vesting-date FMV and share count for each lot from your equity portal or W-2 detail.
Calculate true basis (FMV × shares) for every lot you sold.
Enter each sale on Form 8949 with your real basis in column (e) and code B with an adjustment in column (g).
Carry totals to Schedule D and confirm your gain reflects only post-vesting price change.
File by April 15, 2026 for tax year 2025, or amend with Form 1040-X if you already filed wrong.
Call a CPA if you have ISOs/AMT, multiple states, pre-IPO shares, or dozens of lots.

This article is educational and is not a substitute for advice from a licensed tax professional about your specific situation. When your equity spans AMT, multiple states, or a company that went public or was acquired, a CPA or tax attorney is worth the fee — they will reconstruct your basis, handle multi-state allocation, and respond to IRS notices on your behalf.

FAQs

Is a $0 cost basis on my 1099-B a broker error? No. It is usually correct under IRS rules, which let brokers exclude the wage-income portion of vested shares. You fix it yourself on Form 8949 — the broker will not change the form.

What is my cost basis for vested RSUs? The fair market value on the vesting date. Multiply the per-share FMV by the shares that vested. That same amount was already taxed as wages on your W-2 for the vesting year.

Which form corrects the $0 basis? Form 8949. Enter your true basis in column (e), use code B in column (f), and an adjustment in column (g). Totals flow to Schedule D of your 2025 return.

Will I be double-taxed if I do nothing? Yes. Filing the $0 basis means the income you already paid tax on at vesting gets taxed again as a capital gain, often costing thousands in extra federal tax.

Where do I find my real basis? Your broker’s supplemental statement. It lists the adjusted cost basis per lot. Your equity portal and W-2 detail show the vesting-date FMV as a backup.

Do sell-to-cover shares change my basis? No. Shares withheld to cover taxes are already reflected in your W-2 withholding. You only compute basis on the shares actually delivered to your account.

What if I already filed with the $0 basis? File Form 1040-X. Attach a corrected Form 8949. You generally have three years from your original filing date to claim the refund, so 2025 returns can be amended through about 2029.

What is a CP2000 notice? An automated IRS proposal, not a bill. It flags a mismatch between your return and third-party forms. Respond by the deadline with a corrected Form 8949 to avoid an enforced assessment.

Does my state follow the federal basis fix? Usually, yes. Most income-tax states start from your federal gain, so the correction carries over. No-income-tax states like Texas and Florida do not tax the gain at all.

Does this apply to ESPP and stock options too? Yes. ESPP discounts, NQSO spreads, and some ISO sales also create understated basis on the 1099-B. You add back the income already on your W-2, with ISOs sometimes involving separate AMT basis.

What is the deadline to fix this for tax year 2025? April 15, 2026. That is the filing and payment date. An extension moves filing to October 15, 2026, but any tax owed is still due April 15.

Can I just let my CPA handle it? Yes, but give them the data. Preparers often enter 1099-B numbers as-is unless you hand them the vesting-date FMV and share count for each lot.

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