RSU W-2 and 1099-B: How to Report RSU Income Without Paying Taxes Twice (2026)

Every year, thousands of tech employees overpay taxes because they don't know how to reconcile their W-2 and 1099-B from RSU transactions. The culprit: a $0 cost basis on the 1099-B that looks like a gain you already paid tax on. This guide explains what each form shows, where the trap is, and how to report RSU sales correctly on your 2026 return.

The two-form problem

When your RSUs vest, two separate tax events occur — and two separate IRS forms report them:

1. Vest date (ordinary income event): Your employer reports the fair market value of the shares delivered to you as ordinary income on your W-2. Tax is withheld.
2. Sale date (capital gain/loss event): When you (or your broker, in a sell-to-cover) sell the shares, your brokerage reports the proceeds on Form 1099-B.

Both forms report activity on the same shares. If you report the 1099-B without adjusting the cost basis to match what's already on your W-2, you pay income tax on the same dollars twice — once via W-2, once via Schedule D.

What your W-2 shows for RSU income

When RSUs vest, your employer must withhold employment taxes at the vest date. Here is how each W-2 box reflects RSU activity:

Practical tip: Add up the RSU vesting activity reported by your brokerage platform (usually in a "Tax Center" or "Cost Basis" section) and compare it against the difference between your Box 1 total and your annual salary + bonus. If those numbers don't reconcile, you may be missing a vest event or your employer may have reported a date's FMV differently than your brokerage.

Why you also receive a 1099-B

Your brokerage reports every sale of RSU shares on Form 1099-B — including sell-to-cover transactions that your employer's stock plan administrator executed on your behalf to fund the withholding tax. You receive a 1099-B even if you didn't choose to sell, didn't log into a brokerage, and didn't keep any shares.

The 1099-B captures the capital gain or loss side of the equation — the difference between what you sold the shares for and their cost basis (what they were worth when you received them). If you sold the day they vested, the gain is typically zero or near zero. If you held and then sold later, you owe capital gains tax on the appreciation since vest.

The cost basis trap: the #1 RSU tax mistake

This is where most errors happen. When your RSUs vest, you paid nothing for the shares out of pocket. Your brokerage knows this. So for many RSU transactions — especially at equity plan administrators like Fidelity NetBenefits, Morgan Stanley at Work, E*TRADE, or Charles Schwab Equity Awards — the 1099-B may report your cost basis as:

• $0 (the technical purchase price you paid)
• Blank or "Not reported" (the broker classified shares as "noncovered securities")
• Partially correct (the broker has some data but not the full vest-date FMV)

In all of these cases, the correct cost basis is the FMV of the shares on the vest date — the same amount already reported on your W-2 as ordinary income.⁴ Using a lower basis creates a phantom capital gain you've already paid ordinary income tax on.

Sell-to-cover transactions on your 1099-B

Most companies use sell-to-cover to satisfy RSU withholding: on the vest date, the plan administrator automatically sells a portion of your vested shares (just enough to cover the 22% federal withholding plus state and FICA) and remits the proceeds to the IRS and state.

These forced sales appear on your 1099-B just like voluntary sales. They are taxable events but typically produce zero or near-zero gain because the shares were sold within hours or days of vesting at approximately the same price used to calculate FMV on your W-2.

What to watch for: If the sell-to-cover happened on a different date than the vest date (common when vests fall on weekends or blackout periods), the sale price and the FMV on the W-2 may differ slightly, creating a small short-term capital gain or loss. Report it accurately — it's usually immaterial but still reportable.

How to report RSU sales on Form 8949 and Schedule D

Here is the step-by-step process for correctly reporting RSU share sales on your federal return:

Step 1: Gather your documents

• Your W-2 (Box 1, and the supplemental breakdown if your employer provides it)
• Your 1099-B from the brokerage
• Your broker's Supplemental Information Statement showing vest-date FMV per lot

Step 2: Match each 1099-B lot to a vest event

Each line on your 1099-B represents shares from a specific vest. Match the sale date, number of shares, and proceeds to the corresponding vest event in your supplemental statement. This tells you the correct adjusted basis for each lot.

Step 3: Enter the sale on Form 8949

Form 8949 has separate sections for short-term (held ≤1 year) and long-term (held >1 year) sales. Each RSU lot is typically short-term if you sold it on or shortly after vest; long-term if you held for more than 12 months from the vest date.

• Column (d) — Proceeds: Enter the amount from your 1099-B.
• Column (e) — Cost or other basis: Enter the vest-date FMV per your supplemental statement (the adjusted basis, not the $0 figure your brokerage may have on the 1099-B).
• Column (f) — Adjustment code: If the basis on your 1099-B differs from the correct basis, enter code "B" to indicate a basis correction.
• Column (g) — Adjustment amount: Enter the difference between the correct basis and the reported basis (positive if you're increasing the basis, which reduces your gain).

If your brokerage's 1099-B already shows the correct adjusted basis (some do, especially for "covered securities" acquired after 2011), you can check Box A, B, or C on Form 8949 and enter the amounts as reported — no adjustment needed.

Step 4: Carry totals to Schedule D

Aggregate short-term lots on Schedule D Part I and long-term lots on Part II. The net gain or loss flows to Form 1040 Line 7.

Short-term vs long-term: when holding RSU shares changes your tax rate

If you hold RSU shares after vest instead of selling immediately, the appreciation becomes a capital gain — taxed at lower long-term rates if you hold for more than 12 months from vest date.

Note that holding does not change the ordinary income already recognized at vest — that's fixed. Holding only changes the tax treatment on post-vest appreciation. In California, there is no preferential long-term capital gains rate; CA taxes all capital gains as ordinary income at up to 13.3%.

State tax reporting

California

CA conforms to federal RSU income reporting — the income on your W-2 is California wages. CA supplemental withholding is 10.23% at vest, but California's top marginal rate is 12.3% (plus 1% Mental Health Services Tax above $1 million), so there is typically an under-withholding gap. California has no capital gains preference — all gains are taxed at ordinary income rates on Form 540.

New York

NY W-2 wages include RSU income. If you worked in NY while the RSUs were earning (granted and/or vesting while you were a NY resident or worked there), NY claims tax on that income under its sourcing rules — even if you've since moved. This becomes a multi-state allocation issue if you vested in different states over the grant period.

Moving states between grant and vest

If you moved from California to Texas (or any other state with income tax) between your RSU grant date and vest date, California's Franchise Tax Board allocates a portion of the vest-date income to California based on the proportion of the vesting period you worked in California.⁶ This creates a partial-year CA tax liability even after moving — and requires filing a CA nonresident return. The same logic applies to New York.

How ISOs and NSOs differ — different forms entirely

ISOs (Incentive Stock Options)

When you exercise ISOs, you do not receive income on your W-2 (assuming a qualifying disposition). Instead, your employer sends you Form 3921 — an informational form that shows the grant date, exercise date, exercise price, and FMV on the exercise date. You use Form 3921 to calculate your AMT adjustment. A disqualifying disposition (selling before 2-year grant anniversary / 1-year exercise anniversary) does create W-2 income for the spread.

NSOs (Non-qualified Stock Options)

When you exercise NSOs, the spread (FMV − exercise price) is ordinary income reported on your W-2 Box 12 with Code V. You will also receive a 1099-B when you sell the shares, with the same cost basis reconciliation issue as RSUs.

ESPP

ESPP purchases generate Form 3922 (informational, no immediate tax due). When you sell ESPP shares, the 1099-B reports the sale and your W-2 may include compensation income — the exact amount depends on whether it's a qualifying or disqualifying disposition. The cost basis for ESPP shares is more complex than RSUs; see the ESPP tax guide for details.

The $0 basis on your 1099-B: a timeline of the problem

This issue has a regulatory history worth understanding. Before 2011, brokers were not required to track cost basis at all — it was entirely the employee's responsibility to document the vest-date FMV. After 2011, brokers became required to track basis for "covered securities," but RSU shares have a quirk: they are treated as if you purchased them at $0 (since you paid nothing out of pocket), and some brokerage systems report this $0 purchase price as the basis rather than the compensation income that established the true economic basis.

The IRS is aware of this. Publication 525 (Taxable and Nontaxable Income) states explicitly that the basis for RSU shares equals the amount of compensation income recognized at vesting.⁴ But the 1099-B your broker sends may still show $0. The reconciliation burden falls on you.

What an advisor actually does with your tax forms

Reconciling W-2 to 1099-B for a tech employee with multiple grant dates, sell-to-cover lots, some voluntary sales, a mid-year state move, and possible ISO exercises requires tracking each lot through a multi-step basis calculation. An equity-comp specialist does this as a standard part of annual tax preparation — and will also spot opportunities the forms don't reveal: whether you should accelerate or defer a sale to shift from short-term to long-term rates, whether a wash sale from tax-loss harvesting in adjacent positions is lurking, or whether your AMT credit from prior ISO exercises is available to recover.