About the RSU Tax Calculator
When a batch of Restricted Stock Units vests, the full value of those shares becomes taxable compensation on that day, whether or not you sell a single share. The RSU Vesting Tax Calculator estimates that taxable value, the tax withheld at the federal supplemental wage rate, and how many shares you actually walk away with after your employer sells some to cover the withholding. It's built for employees at companies that grant RSUs who want to know their real share count and cash impact around a vesting date.
How It Works
Enter the number of shares vesting, the share price on the vesting date, and the withholding rate your employer applies (the calculator defaults to 22%, the standard federal supplemental wage rate for amounts under $1 million in a year). It multiplies shares by price to find total vesting value, applies the withholding rate to that value, converts the withheld dollar amount back into an equivalent number of shares, and subtracts those from your total to show net shares received.
Formula & Methodology
This models the common sell-to-cover arrangement, where a brokerage sells just enough freshly vested shares at the vesting-day price to generate the cash needed for withholding, then delivers the remaining shares to your account. Because the sale price and the valuation price are treated as identical in this simplified model, the shares-withheld figure is a direct dollar-to-share conversion at that single price point.
Examples
A typical quarterly vest
500 shares vest at a share price of $40, for a total vesting value of $20,000. At the default 22% withholding rate, $4,400 is withheld, covered by selling 110 shares, leaving 390 net shares deposited into the employee's account.
A larger vest at a higher share price
1,200 shares vest at $85 per share, for a total value of $102,000. Withholding at 22% comes to $22,440, requiring about 264 shares sold to cover, and leaving roughly 936 net shares.
Advantages
- Converts an abstract vesting event into two concrete numbers: the cash withheld and the exact share count landing in the account.
- Makes the sell-to-cover mechanism visible, so the drop in share count at each vest isn't a surprise.
- Lets you test different withholding rates to see how a jump to the 37% supplemental rate on a large vest would change your net share count.
Common Mistakes
- Assuming the 22% withheld at vesting is the final tax owed, rather than a pre-payment reconciled against your actual marginal rate at filing.
- Forgetting that shares withheld for taxes permanently reduce the share count received, not just a cash amount deducted later.
- Treating the vesting-day value as a capital gain rather than ordinary income, which can lead to under-withholding elsewhere.
Edge Cases to Watch For
- The 22% default only applies to supplemental wages up to $1 million in a calendar year; amounts above that threshold are withheld at 37%, which this calculator won't automatically switch to unless you raise the rate yourself.
- Withholding is not your actual tax bill. If your real marginal rate is above the withholding rate, you'll likely owe more at filing; if it's below, you may see a refund.
- The calculator treats shares withheld as a fractional number rather than rounding to a whole share, so the exact count from a real sell-to-cover transaction may differ slightly.
- RSU income here is ordinary income only. Any gain or loss after vesting, once you sell the remaining shares, is a separate capital gains calculation using the vesting-day price as your new cost basis.
Common Use Cases
- Employees checking how many shares will actually land in their brokerage account after an upcoming vest.
- Anyone budgeting cash flow or planning a stock sale around a known vesting date.
- Workers comparing how a higher share price or a shift to the 37% supplemental rate would change their after-tax share count.