RSU Tax Calculator – Tech Stock Vesting, Supplemental Withholding & Capital Gains
How Restricted Stock Units (RSUs) Are Taxed in Tech
For software engineers and corporate leaders at Google, Apple, Meta, Microsoft, and Amazon, Restricted Stock Units (RSUs) form the bedrock of compensation. However, stock equity taxation follows fundamentally distinct rules from standard stock grants:
Tax Event 1: The Vesting Date (W-2 Ordinary Income)
When RSUs vest, they are treated as pure cash compensation. The taxable value is calculated simply as:
Taxable Compensation = Number of Vested Shares × Fair Market Value (FMV) on Vest Date
This amount is subject to Federal Income Tax, State Income Tax, Medicare Tax (1.45% + 0.9% additional surtax), and Social Security Tax (if below the wage cap), appearing directly in Box 1 of your Form W-2.
The 22% Statutory Withholding Trap
By default, IRS regulations mandate that employers withhold a flat 22% federal rate on supplemental wages up to $1,000,000. For mid-level and senior engineers whose household income places them in the 32%, 35%, or 37% tax brackets, this creates an enormous 10% to 15% tax underwithholding shortfall that must be paid in April alongside potential underpayment penalties.
Tax Event 2: Capital Gains Upon Subsequent Sale
Your cost basis in the shares is exactly equal to the FMV on the vest date. If you hold the stock and it appreciates, selling within 12 months triggers ordinary Short-Term Capital Gains. Holding beyond 12 months qualifies for preferential Long-Term Capital Gains rates (0%, 15%, or 20% + 3.8% Net Investment Income Tax).
Frequently asked questions
Should I hold my RSUs or sell immediately upon vest?
Financial fiduciaries generally recommend selling immediately. Holding concentrated stock in the same company that pays your salary exposes you to dual risk—if the company falters, both your paycheck and portfolio plunge.
How do I avoid the RSU tax season surprise?
Instruct your payroll provider (or broker like Morgan Stanley, E*TRADE, or Charles Schwab) to withhold at your true marginal tax rate (e.g. 37%), or submit quarterly estimated tax payments via Form 1040-ES.
Do RSUs require filing an 83(b) election?
No. Form 83(b) elections apply to Restricted Stock Awards (RSAs), not RSUs. RSUs cannot be taxed prior to vesting.
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