RSU Taxes: Vesting, Withholding and What Happens When You Sell

The two-event framework

For a typical U.S. employee RSU, it helps to separate the tax story into two events:

1. Vesting/settlement: compensation income can be recognized when shares or cash are transferred.
2. Later sale: movement in the share price after acquisition can create a capital gain or loss.

Mixing those two events together is the source of many RSU tax mistakes.

RSUs are not stock at grant

A restricted stock unit is generally a promise to deliver stock or cash later if vesting conditions are satisfied. You typically do not own the stock at grant.

That is different from restricted stock that is actually transferred subject to vesting restrictions.

Because an RSU generally is not property at grant, a normal Section 83(b) election is not available for the RSU grant itself.

What happens at vesting?

Suppose 1,000 RSUs vest when the stock is worth $50 per share.

The gross value is:

1,000 × $50 = $50,000

For a typical U.S. employee arrangement, that $50,000 is generally compensation income when the shares are delivered/settled, subject to the applicable payroll and income-tax withholding mechanics.

Your employer may withhold some shares to cover taxes. For example, 300 shares might be withheld and 700 delivered to your brokerage account.

That does not mean the 300 shares represent the exact final tax bill.

Withholding is not the same as tax liability

Withholding is a prepayment.

If the RSU vest pushes total annual income into a higher marginal bracket or combines with bonuses, spouse income, capital gains and other compensation, actual tax liability can be higher than the amount withheld.

The reverse can also happen.

That is why people with large equity-compensation events often need to estimate total-year tax rather than simply looking at the broker's “taxes withheld” line.

Basis matters when the stock is sold

Continuing the example, assume the tax basis for the shares is generally connected to the $50 fair market value recognized when the stock was delivered.

If the employee later sells shares at $60, the post-vesting increase can create a capital gain.

If the shares are sold at $40, the post-vesting decline can create a capital loss.

The compensation was already recognized at vesting. Do not accidentally treat the entire eventual sales proceeds as capital gain.

Holding period starts after shares are acquired

The later gain or loss can be short-term or long-term depending on how long the stock is held after acquisition under the applicable tax rules.

That creates a separate choice: sell immediately, hold for diversification/tax reasons, or hold because you intentionally want employer-stock exposure.

The tax holding period should not be the only factor. Waiting for long-term treatment can expose the portfolio to a large employer-stock decline.

Employer-stock concentration is a real risk

Your salary, future bonuses, career prospects and RSUs may all depend on the same company.

Holding vested shares can increase that concentration further.

A useful question is:

“If I received the same dollar amount in cash today, would I choose to buy this much employer stock?”

That reframes the decision without assuming the answer must be “sell everything.”

Common mistakes

• Thinking RSUs are taxable only when sold.
• Assuming shares withheld for taxes equal the final tax liability.
• Using a zero cost basis when shares were already taxed as compensation.
• Ignoring state taxation.
• Holding solely to reach long-term capital-gain treatment without measuring concentration risk.
• Forgetting blackout periods or company trading policies.
• Treating every equity plan as identical.

A practical checklist after a vest

1. Record number of shares vested.
2. Record fair market value used for compensation.
3. Record shares/cash withheld for tax.
4. Confirm W-2 reporting later.
5. Confirm the brokerage basis before filing a return.
6. Decide intentionally how much employer stock you want to keep.
7. Estimate total-year income tax if the vest is large.
8. Track acquisition date for later capital-gain holding period.

Bottom line

RSUs are easiest to understand as compensation first, investment second. Vesting creates the compensation event; what you do with the stock afterward becomes a portfolio and capital-gains decision. Keep those two decisions separate.