RSU Tax Basis Adjuster
Model corrected cost basis for RSU sales—avoid double taxation on Form 8949 when brokers report $0 basis
Companion guide: RSU Tax Basis Adjuster: Avoid Double Taxation on Form 8949
Why RSU basis imports fail
Ordinary income from vesting usually flows through Form W-2, while Form 1099-B may show proceeds but $0 or incomplete basis. Without overriding basis on Form 8949, tax software can fabricate excess capital gain—even though vest wages were already taxed.
RSU basis calculator inputs and results
RSU sale (per share)
Use vest FMV per share for the lot you sold—typically from employer supplemental statements or vest confirmations.
How wage basis flows into Schedule D
RSUs are taxed as compensation when they vest and settle; later open-market sales are separate capital transactions. Form 8949 bridges broker proceeds with your reconstructed wage-backed basis before Schedule D aggregates net capital gain.
Double-tax failure mode
Accepting $0 basis repeats taxation economically: the vest FMV already flowed through payroll, then uncorrected basis treats nearly all proceeds as capital gain.
Corrective framing
Replace broker basis with wage-backed FMV for the shares sold, document lot sourcing, and reconcile per Instructions for Form 8949. When unsure, engage a CPA/EA with equity experience.