2026 educational tax estimate
2026 RSU Tax & Withholding Gap Calculator
Estimate W-2 income, payroll taxes, federal and state tax, cost basis, and the cash shortfall that sell-to-cover may leave behind.
Calculation methodology reviewed by Carina Luo, CPA
Based on 2026 federal tax rules. Last reviewed July 2026.
Direct answer
RSUs are generally taxed as wages when they vest or settle. A common shortfall occurs when the employer withholds federal income tax at 22% while the employee's incremental federal rate is higher. The calculator stacks the RSU income on top of your other 2026 taxable income and separately estimates payroll and state tax.
Your inputs
Quick estimate
Use expected taxable income after deductions, excluding this RSU vest.
Used to estimate Social Security and Additional Medicare Tax.
22% is common; supplemental wages above $1M for the year are generally withheld at 37%.
Enter zero if unknown for a more conservative cash-gap estimate.
2026
Estimated vesting impact
Estimated additional cash to reserve
$11,150
Incremental tax less estimated federal, state, and payroll withholding.
W-2 income
$50,000
Federal withholding gap
$6,500
Estimated total incremental tax
$23,325
Payroll tax
$1,175
Basis per share
$50.00
Total tax basis
$50,000
Educational estimate only, not tax advice. Final results depend on full income, deductions, residency, prior returns, and transaction records.
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How the estimate works
RSU W-2 income equals shares vested multiplied by vest-date fair market value. Incremental federal tax uses the 2026 ordinary-income brackets. Social Security is limited by the 2026 wage base; Medicare and Additional Medicare Tax are modeled separately. Your per-share tax basis is the vest-date fair market value.
Important limitations
- Actual withholding can use an aggregate payroll method rather than the flat supplemental-wage rate.
- This estimate does not model deductions, credits, prior estimated payments, or multi-state sourcing.
Frequently asked questions
Does sell-to-cover mean all tax is paid?
No. It covers the employer's withholding calculation, not necessarily your final federal and state liability.
What is my RSU cost basis?
For a typical public-company RSU, the vest-date value already included in wages generally becomes the stock's tax basis. Confirm the lot-level records and 1099-B.
What if the stock falls after vesting?
The W-2 wage income is not reversed. A later decline generally produces a capital loss when the shares are sold.