What Does ‘Stock Offset’ Mean on Your Pay Stub?

You open your paystub after a vest and see a line called “stock offset” eating into your take-home pay. No warning, no explanation, just a number. If you’ve never seen it before, it’s easy to think something went wrong. It didn’t. Here’s what it actually means, and why it matters more than most people realize.

What Is a Stock Offset?

A stock offset is how your payroll system accounts for taxes owed on RSU shares that just vested. When your shares vest, the value is treated as taxable income, just like your salary. Your employer has to withhold taxes on that income, the same way they withhold from your paycheck.

The catch is that RSU income isn’t cash. It’s stock. Depending on your employer’s plan, the tax is covered either by selling a portion of your shares (sell-to-cover) or by withholding shares before they ever reach your account (net settlement). Either way, the tax offset shows up the same way on your paystub. It’s not a fee. It’s not a penalty. It’s the tax withholding for the vest, just labeled in a way that isn’t obvious unless someone explains it to you.

This matters more than it might seem, because the stock offset directly affects how many shares you actually end up holding, how much of your income shows up on your W-2, and whether you’ll owe more (or get a refund) when you file. Understanding this one line item is a small piece of a much bigger picture: managing your equity compensation as a whole.

Why It Shows Up as a Separate Line

Your regular paycheck already has its own tax withholding lines: federal, state, Social Security, Medicare. RSU income gets added on top of that as supplemental wages, and it usually gets withheld at a flat supplemental rate rather than your regular marginal rate. That’s why it appears separately instead of blending into your normal withholding lines.

This is also why so many RSU holders end up owing more at tax time, even though taxes were withheld. The federal supplemental withholding rate is 22% for amounts up to $1 million in a calendar year, and jumps to 37% above that. But that 22% is only the federal piece. Your stock offset also covers state income tax (where applicable) and FICA — Social Security (6.2%, up to the annual wage base) and Medicare (1.45%). Combined, total withholding on a vest can realistically land at 30–40% or more, depending on your state and income level.

If you’ve already hit the Social Security wage base ($176,100 in 2026) from your salary, RSU vests later in the year won’t have Social Security withheld, which can make the total offset look lower than earlier vests, even though nothing else about the vest changed. And if your actual marginal tax rate is higher than what’s withheld, you’ll still owe the difference in April.

Who This Catches Most Often

This gap between withholding and what’s actually owed tends to hit a specific group hardest: people whose base salary alone already puts them near the top of the 22% federal bracket, before equity is even added in. If your salary is $150,000 to $250,000 and your RSU income stacks on top of that, there’s a strong chance your real marginal rate on the vest is 32% or higher, while your paystub withholding, even combined with state and FICA, may still fall short.

At incomes above $200,000 (single filers) or $250,000 (married filing jointly), RSU income is also subject to the 0.9% Additional Medicare Tax, one more reason the standard withholding often isn’t enough for higher earners.

It also catches people who have several vesting events throughout the year (monthly or quarterly vesting schedules, common at large tech companies after the initial cliff), because each one under-withholds a little, and those small gaps compound into a real bill by April.

Tax treatment varies by individual circumstances, filing status, state of residence, and total income; the examples below are illustrative. Work with a tax advisor to calculate your specific exposure.

A Few Examples

Example 1: A single vest. Say 100 shares vest at $80 a share. That’s $8,000 of taxable income. Between federal (22%), state, and FICA taxes, your employer withholds shares to cover roughly 30% of that value, say 30 shares, worth $2,400, and that $2,400 shows up as your stock offset. You’re left holding 70 shares outright, and $8,000 has been added to your taxable income for the year, with $2,400 of it already withheld.

Example 2: Stacking vests. Now say you have quarterly vests of similar size throughout the year, four vests totaling $32,000 of RSU income. If each one is withheld at roughly 30% instead of your real 35%+ combined marginal rate, you’re short by a meaningful amount across the year, money you’ll owe when you file, not money that was lost.

Example 3: A high-value single vest. If you have a large one-time vest, say $50,000 worth of shares in a single event, and your combined marginal rate is closer to 40%, a 30% withholding rate leaves a real gap on that vest alone. This is the scenario that surprises people the most, because a single event creates a single, large shortfall.

What Should You Do About It?

• Don’t panic when you see it. A stock offset on its own isn’t a mistake. It’s an expected part of how vests are taxed.
• Check your withholding against your real combined rate. If your true marginal rate (federal, state, and Medicare surtax included) is higher than what’s being withheld, set aside extra to cover the gap, ideally in a separate savings account earmarked for taxes.
• Track it across the year. Multiple vests mean multiple offsets, and it’s easy to lose track of how much has actually been withheld versus what you’ll owe in total.
• Ask about your plan’s withholding options. Most employers apply the IRS supplemental rate automatically with no election available, but some plans do allow you to request additional withholding, check your plan documents or equity platform. You can also increase your W-4 withholding from salary or make quarterly estimated payments to cover the gap.
• Understand what comes next. Once shares land in your account, any future gain or loss is a capital gain, short-term if you sell within a year of vesting, long-term if you hold longer. That’s a separate tax layer worth planning around.

Common Questions

What is supplemental wage withholding?
It’s the IRS category that covers income outside your regular salary, like bonuses and RSU vests. It’s withheld at a flat rate (22% up to $1 million federally) rather than your normal paycheck withholding rate.

Is a stock offset the same as a fee?
No. It’s tax withholding on vested shares, not a charge from your employer or broker.

Why is the number different every time I vest?
It depends on your stock price at vesting, the number of shares vesting, and applicable state and FICA rates. All of these can change from one vest to the next, including whether you’ve already hit the Social Security wage base for the year.

Does the stock offset cover all my taxes on the vest?
Not necessarily, and often not. It typically covers federal supplemental withholding, state tax, and FICA, but if your real marginal rate is higher than that combined total, you’ll owe the rest at filing.

How do I know if I’m under-withheld?
Compare your true combined marginal rate (federal, state, and Medicare surtax if applicable) to the total percentage being withheld on your vest. If your rate is higher, you’re likely under-withheld.

Can I change how much is withheld from my RSU vests?
Most employers apply the IRS supplemental rate automatically with no employee election available. Some plans do allow you to request additional withholding, so check your plan documents. What you can always control is your W-4 withholding from salary or making estimated quarterly payments.

Where do I see the full picture of what I owe?
Your W-2 will reflect the vested income, and your year-end statements will show what was withheld. Comparing the two, ideally with a tax advisor, is the best way to catch a shortfall before it becomes a surprise bill.

Want more on how equity compensation fits into your overall financial plan? Visit my About page to learn how I work with clients, or explore the full Equity Compensation guide for the bigger picture.