Texas Supplemental Tax Regulations for Amazon RSUs
Texas levies zero personal income tax on supplemental wages, RSU vests, or capital gains. Your statutory withholding is restricted exclusively to Federal supplemental (22%/37%) and FICA (Medicare/Social Security).
Texas Safe Harbor & Underpayment Penalties
No state safe-harbor required.
Employer Stock Plan Specifics: Morgan Stanley at Work (Shareworks) / Fidelity
Amazon equity packages are heavily backloaded into years 3 and 4 (40% each year). In year 3, your total W-2 income can leap into the 37% marginal bracket, while Morgan Stanley only withholds 22% federally. Without quarterly estimated payments or selling additional shares, Amazonians face a $15,000–$40,000 tax shock in April.
When vesting at Amazon, Morgan Stanley at Work (Shareworks) / Fidelity calculates automatic sell-to-cover withholding using Texas's statutory supplemental rate of 0.00% combined with the federal supplemental rate (22% on up to $1M). Because top earners in Texas reach marginal brackets exceeding these rates, you will face an incremental shortfall on April 15.
Localized CPA & Advisory Referral
Advisor Guidance: Pair with an Austin tech CPA to model federal safe-harbor withholding and optimize post-vest equity liquidation.