How RSUs Affect Your Tax Refund (and Why You Might Owe)

For years you've counted on a tax refund every April — maybe a few thousand dollars that helped with a vacation or paid down some debt. Then you started receiving RSUs as part of your tech compensation, and suddenly that refund disappeared. Instead of a check from the IRS, you owe $8,000. Or $15,000. Or more.

This is one of the most common financial surprises in the tech industry. It's not a bug — it's a predictable consequence of how RSU withholding works. Understanding why it happens puts you in control of preventing it.

Why RSUs Turn Refunds Into Tax Bills

The core issue is a mismatch between how your employer withholds tax on RSUs and how much you actually owe.

Salary withholding is calculated using your W-4 form, which estimates your tax bracket and adjusts withholding accordingly. If you earn $200,000 and file as single, your employer withholds roughly the right amount of federal tax throughout the year — typically close to your actual liability, which is why you usually get a small refund or owe a small amount.

RSU withholding works completely differently. Under IRS rules, RSU vesting income is "supplemental wages" and is withheld at a flat 22% rate — regardless of your actual tax bracket. There's no W-4 adjustment, no bracket calculation. It's just a flat 22%.

The problem: if your total compensation puts you in the 32%, 35%, or 37% bracket, the 22% withholding on your RSUs falls short by 10-15 percentage points on every dollar of RSU income.

The math:

For someone in the 32% bracket with $100,000 in RSU vesting, that's roughly $10,000 under-withheld on federal tax alone. Add state tax shortfalls (especially in California or New York), and the gap grows.

The "Refund Shock" Timeline

Understanding the timeline helps explain why this surprise hits so hard:

1. January – December: RSUs vest quarterly. Each vest shows up on your pay stub with 22% federal withholding. Everything looks normal.
2. Late January: You receive your W-2 showing total compensation (salary + RSUs). The RSU income is already included in Box 1.
3. February – March: You enter your W-2 in TurboTax or give it to your accountant. The software calculates your actual tax on the full W-2 income.
4. The surprise: Your actual tax is $10,000+ more than what was withheld. Instead of a refund, you owe money — and it's due April 15.

The frustration is compounded by the fact that you may have already "spent" those RSU shares mentally — they vested, you held or sold them, and now months later you're being asked to pay additional tax on income that already felt fully taxed.

Example: Before and After RSUs

Before RSUs (2024):

• Salary: $180,000
• Filing status: Single, no dependents
• Standard deduction: $15,750
• Taxable income: $164,250
• Federal tax: ~$33,000
• Withholding from salary: $34,500
• Result: $1,500 refund

After RSUs (2026):

• Salary: $200,000
• RSU vesting: $120,000
• Total W-2: $320,000
• Standard deduction: $15,750
• Taxable income: $304,250
• Federal tax: ~$69,500
• Withholding from salary: ~$38,500
• Withholding from RSUs (22%): $26,400
• Total withholding: ~$64,900
• Result: owe ~$4,600

The swing is $6,100 — from a $1,500 refund to a $4,600 bill. And this is a relatively modest RSU package. Employees with $200,000+ in annual RSU vesting can face $15,000-$25,000 shortfalls.

It's Not Just Federal Tax

The withholding gap exists at the state level too, though the direction depends on your state:

California: Supplemental withholding rate is 10.23%. For employees with total income in the 9.3% CA bracket, this actually over-withholds slightly. But for income above $371,479 (single), where CA rates jump to 10.3% and then 11.3%, the supplemental rate can under-withhold. Very high earners above $1M face the 13.3% rate (including the 1% Mental Health Services Tax) with only 10.23% withheld.

New York: Supplemental withholding rate is 11.70%. This is actually higher than the top NY state rate of 10.9% for most income levels, meaning NY often over-withholds on RSUs. However, NYC residents face an additional city tax of up to 3.876% that may not be fully covered.

For state-specific details, see our California Income Tax guide and New York Income Tax guide.

How to Estimate Your RSU Impact

Before April surprises you, estimate the impact in advance:

Step 1: Find your total W-2 income (salary + expected RSU vesting for the year)

Step 2: Calculate your approximate federal tax using the 2026 tax brackets

Step 3: Estimate your total withholding:

• Salary withholding: check a recent pay stub and multiply by remaining pay periods
• RSU withholding: multiply expected RSU value by 22% (federal) + your state supplemental rate

Step 4: Subtract total withholding from total tax. If positive, that's your expected shortfall.

Or skip the manual math and use our RSU Calculator, which handles federal, state, FICA, and supplemental withholding calculations automatically.

Three Solutions to Prevent the Surprise

1. Adjust Your W-4

The simplest approach: request additional withholding from your regular paycheck. On your W-4, Line 4(c) lets you specify an extra dollar amount to withhold per pay period.

How to calculate:

1. Estimate your annual RSU shortfall (e.g., $12,000)
2. Divide by remaining pay periods (e.g., 24 semi-monthly = $500 per paycheck)
3. Submit a new W-4 with $500 on Line 4(c)

Advantage: Withholding from paychecks is treated as paid evenly throughout the year, even if you increase mid-year. This means no quarterly deadlines and no underpayment penalties.

2. Make Quarterly Estimated Payments

Use IRS Form 1040-ES to make payments directly to the IRS each quarter. This gives you more control over timing and cash flow.

Due dates: April 15, June 16, September 15, January 15.

For a complete walkthrough, see our guide to estimated taxes on RSU income.

3. Sell More Shares to Cover

If your company allows "sell-to-cover" at vesting, you can typically specify a higher coverage ratio. Instead of the default sell-to-cover (which covers only the 22% federal + state supplemental + FICA), you may be able to request a higher percentage.

Check with your company's stock plan administrator (typically Fidelity, Schwab, E*Trade, or Morgan Stanley) about adjusting your sell-to-cover ratio. Some plans allow you to sell enough shares to cover your estimated marginal rate instead of just the supplemental rate.

When RSUs Actually Increase Your Refund

In rare cases, RSU withholding can make your refund larger:

• Low total income: If your total W-2 (salary + RSUs) puts you in the 10% or 12% bracket, the 22% supplemental withholding over-withholds. This is uncommon in tech.
• State over-withholding: As noted above, New York's 11.70% supplemental rate exceeds the actual marginal rate for many income levels, creating state-level over-withholding.
• Large FICA over-withholding: If RSU vesting pushes your wages above the Social Security wage base, you may get a refund from excess FICA withholding (see below).

FICA Over-Withholding: The Hidden RSU Refund

One often-overlooked source of RSU-related refunds is Social Security tax over-withholding. Here's how it works:

The Social Security wage base for 2026 is $176,100. You pay 6.2% Social Security tax on every dollar of wages up to this cap — and nothing above it. Your employer is supposed to stop withholding once you hit the cap.

The problem: When RSUs vest, they're treated as separate supplemental wage payments. Your payroll system may not correctly track cumulative wages across salary + RSU vests, especially late in the year.

Scenario:

• Base salary: $180,000
• RSUs vest in December: $60,000
• Your salary already exceeded the $176,100 SS cap
• Your employer withholds 6.2% on the RSU vest anyway: $3,720 in excess Social Security tax

How to check: Look at your W-2 Box 4 (Social Security tax withheld). If it exceeds $10,918 (which is 6.2% × $176,100), you've been over-withheld. Claim the excess on your tax return — this alone can produce a $2,000-$4,000 refund.

Which Approach Is Right for You? Decision Tree

Not sure whether to adjust your W-4, make estimated payments, or increase your sell-to-cover ratio? Here's a quick decision tree:

Is your RSU vesting predictable and spread evenly through the year?

• Yes → Adjust your W-4 (Line 4(c)). It's the simplest approach with zero penalty risk.

Do you have one or two large cliff vests per year?

• Yes → Make quarterly estimated payments. You have more control over timing and amounts, and you keep your paycheck intact.

Have you already exceeded the 22% supplemental rate gap? (i.e., you're in the 24% bracket or lower)

• Yes → You may not have a shortfall at all. Run the numbers with our RSU Calculator before making changes.

Are you already over-withheld from salary? (e.g., you typically get a large refund)

• Yes → Neither — your salary over-withholding may offset the RSU under-withholding. Check the net position first.

Do you want to keep cash invested as long as possible?

• Yes → Estimated payments on the quarterly deadlines. You keep the cash working until each due date.
• No, I prefer to not think about it → W-4 adjustment. Set once, forget it.

For a deeper breakdown of withholding mechanics, see our RSU tax rate guide and our quarterly estimated tax guide.

The Bigger Picture

RSU tax planning isn't just about avoiding a surprise bill — it's about understanding your total compensation. When you receive an offer with "$100,000 in RSUs," the after-tax value is closer to $55,000-$65,000 depending on your bracket and state. Knowing this helps you:

• Negotiate compensation with realistic expectations
• Budget for tax obligations throughout the year
• Decide whether to hold or sell vested shares
• Plan estimated payments or W-4 adjustments proactively

For a complete overview of how RSUs flow through your tax return, see our guide on how equity compensation affects your tax return. For the underlying bracket math, reference our 2026 federal tax brackets.

Frequently Asked Questions

Why do RSUs cause me to owe money at tax time? Because your employer withholds only 22% federal tax on RSU income (the flat supplemental rate), but your actual marginal rate is likely 32-37% if your total compensation exceeds $250,000. That 10-15 percentage point gap on every RSU dollar adds up — on $100,000 in RSU vesting, you could be $10,000-$15,000 short. Add state taxes (especially in California at 13.3%), and the shortfall grows further.

Can RSUs increase my tax refund? Yes, in specific cases. If your total income keeps you in the 10% or 12% bracket, the 22% supplemental withholding over-withholds. New York's 11.70% supplemental rate also over-withholds for most state brackets. And if RSU vesting pushes your wages above the Social Security wage base ($176,100), you may get a FICA refund of $2,000-$4,000. Check your W-2 Box 4 to see if Social Security tax exceeds $10,918.

Is 22% withholding enough for RSUs? Almost never for tech employees. If your total compensation (salary + RSUs) exceeds $103,350 (where the 24% bracket starts), you're already under-withheld. For employees in the 32% or 35% bracket — common at total comp of $250,000-$650,000 — the gap is 10-13 percentage points per RSU dollar. Use our RSU Calculator to find your exact shortfall.

Should I adjust my W-4 when RSUs vest? Yes, especially if this is your first year receiving RSUs. The simplest fix is adding extra withholding on Line 4(c) of your W-4. Divide your estimated annual RSU shortfall by your remaining pay periods. For example, a $12,000 shortfall with 24 remaining semi-monthly paychecks means adding $500 per paycheck. The IRS treats paycheck withholding as paid evenly all year, so there's no penalty risk even if you adjust mid-year.

How do I avoid owing taxes on RSU income? You can't avoid the tax itself — RSU vesting is ordinary income. But you can avoid the surprise by closing the withholding gap in advance. Three approaches: (1) increase W-4 Line 4(c) for extra paycheck withholding, (2) make quarterly estimated payments via IRS Form 1040-ES, or (3) request a higher sell-to-cover ratio from your stock plan administrator. Most employees find the W-4 adjustment simplest.