1099-B RSU Adjustment Helper
Structured helper for RSU 1099-B problems — zero basis, duplicate wage reporting, and supplemental plan lot details.
Your broker 1099-B shows $0 basis on RSU shares or TurboTax imported a huge capital gain. This helper calculates the Form 8949 adjustment using vest FMV — the wage income already on your W-2.
Gather before you start
- for the sale (proceeds and reported basis, often $0).
- confirmation with per share on the acquisition date.
- for the year to confirm wages were reported.
- Broker supplemental stock plan statement if available.
Illustrates adjustment math only. Software field labels vary by product and year.
In plain terms
Planning estimate
This is a workflow helper to spot why your 1099-B might look wrong, not a tax-filing engine. It does not tell you which form line to use. Confirm any adjustment with your tax software or a tax professional.
We do not pre-fill personal financial values. Estimates appear only after you enter your own numbers.
Enter your details to estimate
Add your equity, income, state, and withholding details to see an educational estimate. No personal financial values are pre-filled.
Start with the fields below.
Your details
Enter your own numbers below. This is an estimate, not a filing position.
RSU vest value is usually included in W-2 Box 1 wages.
Required to estimate
Fair market value when the shares vested, usually the correct basis.
Required to estimate
Often $0 for RSUs. Enter the total basis your broker reported, or leave blank for $0.
Gross proceeds reported on your 1099-B for this sale.
Required to estimate
Brokers often provide a supplemental statement with the adjusted basis.
Results will appear here once you enter the required details on the left.
Related guides
- RSU Sale Reported Twice: What To Check
Double-counting usually means basis was not adjusted — fix basis before panicking about tax owed.
- Why Is My RSU Cost Basis Zero?
Zero basis on 1099-B usually means the broker did not link your vest wage income — not that tax was skipped.
- How to Adjust RSU Cost Basis
Basis adjustments connect vest wage income to later sales — document FMV from vest records.
- RSUs on 1099-B: What to Look For
1099-B for RSUs often shows low or zero basis — that does not mean your true basis is zero.
When to use this calculator
- You are entering sales on Form 8949 and need the adjustment amount when broker basis is $0 or too low.
- You want a step-by-step reconciliation between wages and proceeds before filing.
- Tax software imported broker data and overstated — you need the basis correction math first.
Inputs you need
- proceeds and reported basis (often $0 for sales).
- Number of shares sold and -date per share from confirmations.
- Holding period (date acquired from , date sold from ).
How to interpret the result
- The helper shows corrected basis and the adjustment to enter on Form 8949 (typically basis reported on that differs from your records).
- after adjustment should reflect post- price movement, not the entire sale price.
- Keep a worksheet tying each share lot to a — mixed lots need separate lines on Form 8949.
What this calculator does not know
- Whether your broker will file a corrected after you contact them.
- Specific tax software field labels — import flows vary by product.
- Alternative minimum tax or NIIT effects from the sale.
- Non- acquisitions (, options exercised) sold in the same lot unless you enter correct basis.
Documents to verify before filing
- Original and supplemental forms.
- notices with for each acquisition date.
- and employer equity tax summary.
- Prior-year return if you carried basis adjustments forward.
Next pages to read
These links are for education and planning. They are not filing instructions and do not replace review of your own documents or a qualified tax professional.
How the tax works
Brokers frequently report noncovered sales with blank or zero basis.
is wage income on — that same amount is generally your per share.
Tax software imports literally unless you enter an adjustment on Form 8949.
What to check on your end
- Corrected basis = × shares sold.
- Adjustment = corrected basis minus reported basis.
- Gain after adjustment vs. price change since only.
- Whether Box 1 includes the income for that lot.
Deleting the 1099-B to avoid double tax
What to pull from your files
- Boxes 1d and 1e.
- confirmation PDF.
- and any wage memo.
- Supplemental lot detail from broker.
Example scenario (hypothetical)
Illustration only, not your tax situation.
Questions people ask
- What adjustment code do I use for RSU basis?
- Form 8949 instructions describe codes when basis reported to the IRS differs from your records. Many sales use a basis adjustment with documentation from confirmations — confirm the code for your tax year in IRS instructions.
- Was my RSU income already on my W-2?
- Standard vests are included in Box 1 wages. That is why basis should reflect — you are not taxed twice when basis is corrected.
- How is this different from the cost basis calculator?
- Same math — this helper emphasizes the adjustment workflow and reconciliation for filing season.
When a CPA is worth it
- Multiple lots sold on one line.
- wages do not match your confirmations.
- You already filed with $0 basis and need to amend.
Sources and notes
Primary tax claims on this page are supported by the official and secondary sources below. Broker and software links describe reporting mechanics — confirm rules against IRS or state guidance.
Calculator outputs are planning estimates with labeled assumptions — not a filing position.
- IRS Publication 15 (Circular E) — Supplemental wages
Internal Revenue Service · Official
Section 7 describes supplemental wage withholding, including the optional 22% flat rate and 37% rate above $1 million of supplemental wages in a calendar year.
- IRS Tax Withholding Estimator
Internal Revenue Service · Official
Tool to estimate whether paycheck withholding (including supplemental events) will cover annual tax liability.
Related calculators
Related pages
- Are RSUs Taxed Twice?
Vest income and later sales can both show up on tax forms — that is not always double tax on the same dollars.
- How to Adjust RSU Cost Basis
Basis adjustments connect vest wage income to later sales — document FMV from vest records.
- RSUs on 1099-B: What to Look For
1099-B for RSUs often shows low or zero basis — that does not mean your true basis is zero.
For learning, not filing
VestingTax.com is not a CPA firm or tax preparer. Grants, employers, and states all differ. Use the cited IRS and state sources above, your own documents, and a qualified tax professional before you make decisions from this guide.