Washington Supplemental Tax Regulations for Amazon RSUs
Washington imposes 0% personal state income tax on W-2 wage income and RSU vests. However, when you subsequently sell shares that have appreciated post-vest, long-term capital gains exceeding $262,000 are subject to the 7% WA Capital Gains Excise Tax.
Washington Safe Harbor & Underpayment Penalties
No state wage safe-harbor required. Only federal 1040-ES applies.
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 Washington's statutory supplemental rate of 0.00% combined with the federal supplemental rate (22% on up to $1M). Because top earners in Washington reach marginal brackets exceeding these rates, you will face an incremental shortfall on April 15.
Localized CPA & Advisory Referral
Advisor Guidance: Work with a Washington State fiduciary advisor to navigate the 7% WA Capital Gains Excise Tax on secondary share sales.