Last Updated: April 2026
Restricted Stock Units (RSUs) are the dominant form of equity compensation at large US tech companies, and they create a predictable but widely misunderstood tax problem. The gap between what your employer withholds on each vest (22% flat) and what you actually owe in federal and state income tax (potentially 24–37%) generates surprise tax bills every April for thousands of employees. This guide explains exactly how RSU taxation works in 2026, why the withholding gap exists and how to calculate it, what FICA taxes apply to vests, how state income tax layers on top, and — critically — what you can do before filing season to close the gap or avoid the underpayment penalty entirely. All calculations use the verified 2026 IRS figures from IRS Revenue Procedure 2025-32.
Understanding RSU taxation requires mapping the lifecycle clearly, because different tax rules apply at each stage.
Grant date: No tax event. You receive a promise of future shares contingent on remaining employed (and sometimes meeting performance targets). The grant price is irrelevant for tax purposes — RSUs have no exercise price.
Vesting date: This is the primary tax event. On the day RSUs vest, shares are delivered and the FMV is treated as ordinary wage income. Your employer reports this on your W-2, withholds income tax (22% flat federal), FICA (Social Security and Medicare), and any applicable state income tax. Most companies use sell-to-cover: they sell enough shares at vest to fund the withholding, and you receive the net shares.
Holding period begins at vest: Your capital gains holding period starts on the vest date, not the grant date. To qualify for long-term capital gains treatment on any post-vest appreciation, you must hold shares for more than 12 months after the vest date.
Sale date: Capital gain or loss event. The difference between the sale price and the vest-date FMV is a capital gain (if positive) or loss (if negative). Short-term if sold within 12 months of vest; long-term if sold after. The vest-date FMV (your cost basis) is reported on Form 1099-B — verify that your broker is using the correct basis, as errors are common with RSU shares.
The withholding gap is the difference between what your employer withholds (22% flat) and what you actually owe (your marginal federal rate on the vest). Here is the step-by-step calculation using the marginal subtraction method — the same method used by the RSU Tax Calculator.
Step 1: Calculate federal income tax on your salary alone (using 2026 brackets, minus the $16,100 standard deduction for single filers).
Step 2: Calculate federal income tax on salary plus RSU vest value combined (same method).
Step 3: Subtract Step 1 from Step 2. The result is the federal income tax attributable to the RSU vest at your marginal rate.
Step 4: Calculate what was withheld: RSU vest value × 22%.
Step 5: Gap = Step 3 minus Step 4. A positive result means you will owe this amount at filing (or in quarterly estimated payments). A negative result means you were over-withheld on the vest.
Worked example: $150,000 salary + $50,000 RSU vest, single filer, 2026. Federal tax on $150K salary (taxable $133,900) = $24,734. Federal tax on $200K combined (taxable $183,900) = $36,734. Federal tax on vest = $36,734 − $24,734 = $12,000. Employer withheld: $50,000 × 22% = $11,000. Gap = $1,000. This employee will owe an additional $1,000 in federal income tax — just from the RSU vest — unless they make a quarterly estimated payment or adjust their W-4.
The 22% flat rate is the default for supplemental wages, but IRS Publication 15 gives employers an alternative: the aggregate method. Under this method, the employer adds the RSU vest value to the employee's regular salary for the pay period and applies the normal payroll withholding tables to the combined amount. The result is withholding that closely approximates the employee's actual marginal rate — eliminating or substantially reducing the withholding gap.
Large public companies (particularly in tech) almost universally use the flat 22% supplemental rate because it is simpler to administer across thousands of employees with different tax situations. Smaller companies and those with more customised payroll setups occasionally use the aggregate method.
How to tell which method your employer uses: check your vest confirmation email or equity platform statement. If withholding is listed as exactly 22% of the gross vest value, your employer uses the flat rate. If the withholding percentage varies or is listed as 24–37%, your employer may be using the aggregate method. In either case, verify your actual marginal rate with the RSU Tax Calculator and compare it to what was withheld.
RSU vest income is ordinary income for state income tax purposes in virtually all states that have an income tax. The key variations:
No income tax states (0% RSU state tax): Alaska, Florida, Nevada, New Hampshire, South Dakota, Tennessee, Texas, Washington, Wyoming. For tech workers who can choose their state of work or residence, these nine states eliminate state income tax on RSU vests entirely.
Flat-rate states: Illinois (4.95%), Pennsylvania (3.07%), Colorado (4.4%), Michigan (4.25%), Arizona (2.5%), Indiana (3.05%), Kentucky (3.5%), Massachusetts (5.0%), Utah (4.55%). RSU vests are taxed at the same flat rate as all other income — simple and predictable.
High-tax progressive states: California (up to 13.3%), New York (up to 10.9%, plus NYC local up to 3.876%), New Jersey (up to 10.75%), Oregon (9.9%), Minnesota (9.85%). These states can add $5,000–$7,000+ in state tax on a $50,000 vest for high earners.
Multi-state vesting (sourcing rules): If your RSU grant spans time when you worked in more than one state, the vest income may be apportioned between states using a time-based formula. Example: if you worked in California for 18 months and New York for 6 months during a 24-month vesting period, then 75% of the vest is California-source income and 25% is New York-source income. Both states may claim their share. This is particularly relevant for remote workers who changed states mid-vest. For a detailed state-by-state breakdown, see the RSU Tax Calculator.
The withholding gap is not inevitable — it can be closed or significantly reduced with these approaches.
1. Adjust your W-4 (simplest option): After a vest event, submit a new W-4 to your employer increasing the additional withholding amount in Step 4(c). Calculate the gap, divide by remaining pay periods in the year, and enter that dollar amount. Your payroll will withhold the extra from each subsequent paycheck — no separate estimated payments needed.
2. Make quarterly estimated payments via IRS Direct Pay: Pay the gap directly to the IRS at directpay.irs.gov within a few weeks of the vest date. Use the estimated payment option (Form 1040-ES). This is the cleanest approach if you have the cash from a sell-to-cover and don't want to alter your W-4. The IRS penalty for underpayment only applies if you owe more than $1,000 and did not meet the safe harbour threshold.
3. Maximise 401k contributions in the vest year: Pre-tax 401k contributions ($23,500 in 2026, $31,000 if 50+) reduce your federal and most state taxable income. Every dollar deferred reduces the income that RSU vests land on top of, potentially keeping you in a lower bracket. The marginal effect is most powerful when a 401k contribution would move your combined income from the 32% to the 24% bracket.
4. Contribute to an HSA: If enrolled in a high-deductible health plan, HSA contributions ($4,300 individual / $8,550 family in 2026) reduce federal AGI. Like 401k contributions, this lowers the taxable income base beneath your RSU vests.
5. Donate appreciated shares to a Donor-Advised Fund (DAF): If you hold vested shares that have appreciated since vest, donating them to a DAF avoids capital gains tax on the appreciation (both federal and California) and generates a charitable deduction at the FMV on the donation date. The shares are sold by the DAF tax-free and the proceeds can be granted to charities of your choice. This does not reduce the ordinary income tax at vest but eliminates any post-vest capital gains tax, which can be material for long-term holders in high-tax states.
US citizens and Green Card holders must file US tax returns regardless of where they live or work, and RSU vest income is included in worldwide income regardless of the country of vesting. Two specific issues arise for internationally mobile employees:
FEIE does not apply to RSU income: The Foreign Earned Income Exclusion (FEIE — Form 2555) excludes certain foreign-earned wages from US tax. However, RSU vest income is classified as US-source compensation (generally) and does not qualify as 'foreign earned income' under the IRS rules. Do not attempt to exclude RSU vest income via FEIE — it is not permitted and will trigger penalties if caught. Source: IRS Revenue Ruling 2004-4.
Foreign Tax Credit (FTC) may apply: If you are genuinely resident in a foreign country and pay foreign income tax on the same RSU vest income, you may be able to claim a Foreign Tax Credit (Form 1116) to offset your US tax dollar-for-dollar. The FTC calculation is complex — particularly for countries with different tax years or rates — and often requires specialist advice. See the RSU Tax for Expats guide for detailed country-by-country analysis.
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File Your RSU Tax Return with TFX →RSUs are taxed on the vesting date — the date the shares are actually delivered to you. This is when the fair market value becomes ordinary income and appears on your W-2. There is no tax at grant. There is no tax at the end of the vesting period if shares are not yet delivered. The vest date (sometimes called settlement date) is the trigger. If you have a quarterly vest schedule, you have four separate taxable events per year, each calculated at the FMV on that specific vest date.
22% flat for cumulative supplemental wages under $1,000,000 in the calendar year, per IRS Publication 15 (Circular E). For vest amounts that push your total supplemental wages above $1,000,000 in a single calendar year, the rate increases to 37% on the excess. These rates apply to the vest value before any sell-to-cover. The 22% rate is not a function of your actual marginal bracket — it is a statutory flat rate that may be higher or lower than your real tax liability.
Standard RSUs do not permit deferral of ordinary income tax. The tax is due at vest regardless of whether you hold or sell the shares. Some companies offer RSU deferral plans (under Section 409A of the Internal Revenue Code), which allow employees to elect deferral before the vesting schedule begins — but these plans are rare and have strict election timing rules. Section 83(b) elections, which can defer tax for restricted stock grants, are not available for RSUs because RSUs are not property (they are contractual promises). If deferral is important to you, ISOs (Incentive Stock Options) may offer more flexibility — see the RSU vs Stock Options guide.
Your cost basis in vested RSU shares is the fair market value (FMV) on the vest date — the same value that was reported as ordinary income on your W-2. If you vest 100 shares at $50/share, your cost basis is $5,000 (or $50/share). If you later sell those shares at $70/share, your capital gain is $20/share ($2,000 total). The capital gain is long-term if you held the shares for more than 12 months after the vest date. Check your Form 1099-B each year — brokers frequently under-report cost basis for RSU shares, which would cause you to pay capital gains tax on income that was already taxed as ordinary income at vest.
Social Security (6.2%) applies to RSU vest income up to the 2026 wage base of $184,500. This limit applies to the combined total of salary and RSU vest income for the year. If your salary alone exceeds $184,500, no Social Security tax applies to the RSU vest. If your salary is below $184,500, Social Security applies to the RSU vest up to the remaining room. Medicare (1.45%) applies to all RSU income with no cap, plus an additional 0.9% on combined wages above $200,000 single / $250,000 MFJ.
Yes. Each individual vest is withheld at the 22% flat rate. But your actual marginal rate is determined by your cumulative income for the year. If you have four quarterly vests of $20,000 each ($80,000 total) on top of a $150,000 salary, each vest is withheld at 22% ($4,400 each). But your actual marginal rate on each vest is 35% (you are already in the 35% bracket on all four). The annual gap is ($80,000 × 35%) − ($80,000 × 22%) = $28,000 − $17,600 = $10,400. This is why tech workers with annual vests of $50,000–$200,000 can face very large April tax bills.
Unvested RSUs are forfeited when you leave employment — they are not transferable or cashable. Vested RSUs that have already been delivered to you are yours to keep. Some companies offer accelerated vesting on termination (especially in merger/acquisition scenarios) — check your RSU agreement. Tax implications on departure: any unvested RSUs that are accelerated and vest on your termination date are still treated as ordinary income at that vest-date FMV. If you move states on departure, the vest may be taxed by both your old and new state depending on sourcing rules.
Yes, if you are a US citizen or Green Card holder. US citizens are taxed on worldwide income regardless of where they live or work. RSU vest income is included. The Foreign Earned Income Exclusion (FEIE) does not apply to RSU income — RSUs are not 'foreign earned income' under IRS Revenue Ruling 2004-4. If you paid foreign income tax on the same vest, a Foreign Tax Credit (Form 1116) may offset some or all of the US tax. See the RSU Tax for Expats and International Workers guide for detailed country-by-country treatment.
The IRS charges an underpayment penalty (Form 2210) if you owe more than $1,000 at filing AND did not meet the safe harbour threshold. Safe harbour: pay the lesser of (a) 90% of the current year's tax, or (b) 100% of last year's tax (110% if prior year AGI exceeded $150,000). Most RSU recipients with a withholding gap can avoid the penalty by making a quarterly estimated payment shortly after each vest event. Pay within a few weeks of the vest at directpay.irs.gov. The current underpayment penalty rate is approximately 8% annualised — not catastrophic, but avoidable.
This is an investment and personal finance decision, not a tax one — but there are two tax angles worth noting. First, if you hold shares and they appreciate, that gain is taxed at long-term capital gains rates (0%, 15%, or 20% federal) if held more than 12 months — potentially much lower than your ordinary income rate. Second, holding concentrates your investment in your employer's stock, adding correlation risk between your employment income and investment returns. Most financial planners recommend selling at least a portion of RSU shares at vest (which you must do anyway for sell-to-cover withholding) to avoid concentration risk. The tax case for holding depends on your expected marginal rate, state of residence, and conviction about the stock.