New York Supplemental Tax Regulations for Microsoft RSUs
New York State Department of Taxation and Finance applies statutory supplemental withholding. For New York City residents, combined state and local marginal rates can exceed 14.77%, causing a severe gap between statutory sell-to-cover and true combined liability.
New York Safe Harbor & Underpayment Penalties
Requires quarterly IT-2105 filings when tax withheld is over $300 below true tax.
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 New York's statutory supplemental rate of 11.70% combined with the federal supplemental rate (22% on up to $1M). Because top earners in New York reach marginal brackets exceeding these rates, you will face an incremental shortfall on April 15.
Localized CPA & Advisory Referral
Advisor Guidance: Consult a New York Tri-State CPA specializing in NYS Form IT-2105 and NYC local tax equity withholding safe harbors.