Washington Supplemental Tax Regulations for Microsoft 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: Fidelity Investments
Microsoft employees in Redmond, WA enjoy 0% state income tax on vesting wages, but face the full federal marginal spread. For senior SDEs and Partners whose base exceeds the $184,500 Social Security cap, every incremental vest dollar is taxed at 35% or 37% plus 2.35% Medicare.
When vesting at Microsoft, Fidelity Investments 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.