You are organizing paperwork for filing season or after a vest, exercise, or sale — and want to know what each document proves (and what it cannot prove).
Start here
What you need before using this
- Access to your equity portal and brokerage account.
- Last year's filed return if you adjusted basis.
- Employer stock plan administrator contact if forms look missing.
Form labels and employer reporting practices vary. Cite your actual forms when working with a preparer.
Why this happens
: Reports wages including income and spread at exercise in Box 1. Also shows federal and state . What it proves: employer reported wage income to the IRS. What it cannot prove: correct on a later share sale — that comes from tied to specific lots.
: Reports proceeds from selling shares. Brokers often show $0 or incomplete basis for sales because they may not track -date . What it proves: sale date and proceeds. What it cannot prove: that is correct without adjusting basis to wages already on .
Form 8949 / Schedule D: Where you report sales with basis adjustments when is wrong. What it proves: your reconciliation between broker data and your records. What it cannot prove: itself — it depends on and confirmations being correct.
Broker supplemental statement: Many brokers issue a second statement with tax lots, acquisition dates, and sometimes corrected basis. Always check for a supplemental before importing into software.
Form 3921: Issued for exercises — shows exercise date, shares, strike, and . What it proves: exercise occurred for and disposition tracking. What it cannot prove: your final — that requires Form 6251 with your full return.
confirmations: From your equity portal — shares, , , net delivery. What they prove: per-share basis at for . What they cannot prove: state sourcing if you moved — you need residency records too.
Exercise notices: For options — spread, shares, . What they prove: exercise date and price for basis and wage income. What they cannot prove: holding period qualification for treatment on a later sale.
State move records: Lease, domicile, employer remote-work policy. What they prove: residency timeline for state returns. What they cannot prove: how each state sources income — rules vary by state law.
What to check
- Box 1 includes values from confirmations.
- basis matches per lot sold.
- Form 3921 matches exercises you recorded.
- Supplemental broker statement arrived after original .
- purchase confirmation matches discount income if reported.
- 83(b) proof of mailing if you early-exercised.
- Two states' forms if you moved mid-year.
Trusting imported 1099-B basis without vest confirmations
What to check in your documents
- and employer equity tax summary.
- All forms and supplemental statements.
- Form 3921 for each exercise.
- and exercise PDFs from equity portal.
- Trade confirmations for sale dates and proceeds.
- Prior-year basis adjustment worksheet if carryforward lots.
Example scenario (hypothetical)
Illustration only, not your tax situation.
Questions people ask
- Is there a separate IRS form just for RSUs?
- No single -only form. income flows through wages; sales use and Form 8949 like other stock sales, with basis tied to .
- Why did I get Form 3921 and a W-2?
- exercises generate Form 3921 for tracking. If you also had vests or exercises, wage income still appears on .
- Can my broker fix 1099-B basis?
- Sometimes, if you provide data. Many taxpayers adjust on Form 8949 themselves using confirmations.
- How is this different from the RSU documents checklist?
- The checklist is a quick gather list before filing. This guide explains what each document type proves and how they fit together across , options, and .
When to get help from a tax pro
- wages do not match your confirmations.
- You have from prior years and disposition sales.
- Multiple brokers or platforms reported sales.
- You moved states with equity events in both states.
Related calculators
- RSU Cost Basis Calculator
Cost basis on sold RSUs usually ties back to vest FMV already taxed as wages. this tool helps you model that link.
- 1099-B RSU Adjustment Helper
Structured helper for RSU 1099-B problems. zero basis, duplicate wage reporting, and supplemental plan lot details.
- RSU Tax Calculator
Model federal and state taxes on your RSU vest, compare withholding to estimated tax, and see what you may keep.
Related pages
- RSU Tax Documents Checklist: What to Save Before You File
Collect documents as vests happen so filing season is paperwork, not archaeology.
- RSUs on W-2: What to Look For
Your W-2 should reflect RSU vest income in wages. know which boxes to check before filing.
- 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.
- How to Adjust RSU Cost Basis
Basis adjustments connect vest wage income to later sales. document FMV from vest records.
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.
W-2 wage reporting, 1099-B proceeds, and ISO Form 3921 reporting.
- About Form 1099-B — Proceeds from Broker and Barter Exchange Transactions
Internal Revenue Service · Official
Broker reporting of sales proceeds and basis; basis on 1099-B may be incomplete for equity-compensation shares.
- IRS — U.S. taxation of stock-based compensation (RSU vesting and W-2 reporting)
Internal Revenue Service · Official
Describes RSU income at vest, W-2 reporting in boxes 1/3/5, and ordinary income treatment.
- Filing taxes for restricted stock, RSUs, or performance awards (tax guide PDF)
Fidelity Stock Plan Services · Brokerage explainer
Explains W-2 vest income, 1099-B with $0 basis, supplemental adjusted cost basis, and Form 8949 reporting.
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.