Sell to cover means your broker automatically sells just enough of your vesting equity compensation shares on the open market to pay the taxes triggered by the vest, then deposits the remaining shares into your account. You don’t spend any personal cash, and you don’t place the trade yourself. The method is most common with Restricted Stock Units (RSUs), and it also works for stock options with one added wrinkle: the sale has to cover the exercise price too.
How the Transaction Runs on Vest Day
On your vesting date, the brokerage administering your company’s equity plan looks at the fair market value of the stock and applies your employer’s withholding rates. Those two inputs decide how many shares get sold. The broker places a market order for exactly that number, sends the cash proceeds to your employer’s payroll department, and drops the leftover shares into your brokerage account as “net shares.” You own them outright from that moment.
A simple example makes the math concrete. Say 500 RSU shares vest when the stock is trading at $100, giving the award a $50,000 gross value. If combined federal, state, and payroll withholding comes to 30%, the broker sells 150 shares to raise $15,000 for the tax bill. The other 350 shares land in your account. You can hold them or sell them later on your own schedule.
The whole process is automated. You don’t find buyers, run the share-count math, or pick a trade time. The broker executes at the market price when the vest processes. Some plans have a short lag between the vesting date and the actual share delivery, which can shift the price used for the tax calculation slightly.
Stock Options Work a Little Differently
With RSUs, the only cost at vesting is the tax, because the shares are delivered to you at no purchase price. Stock options carry a second cost: the strike price you agreed to when the option was granted. When you exercise options through sell to cover, the broker sells enough shares to pay both the strike and the taxes on the spread between strike and market. A larger share of the grant gets liquidated, and you keep fewer net shares.
If you exercise 500 options with a $40 strike when the stock is at $100, the broker has to raise $20,000 for the exercise cost and cover taxes on the $30,000 of spread income ($60 per share times 500). That combined obligation can easily eat more than half the shares.
What the Sale Actually Pays For
The cash from the sold shares satisfies the tax withholding your employer is required to remit on equity income. RSU income and option spread income are treated as supplemental wages. Federal withholding on supplemental wages is a flat 22% up to $1 million in a calendar year, and 37% on the portion above $1 million.1Internal Revenue Service. Publication 15 (2026), (Circular E), Employer’s Tax Guide
On top of that, the sale covers FICA payroll taxes: 6.2% for Social Security up to the annual wage base of $184,500 in 2026, and 1.45% for Medicare with no cap.2Office of the Law Revision Counsel. 26 USC 3101 – Rate of Tax3Social Security Administration. 2026 Cost-of-Living Adjustment (COLA) Fact Sheet An additional 0.9% Medicare surtax applies once total compensation crosses $200,000 for single filers or $250,000 for joint filers.4Internal Revenue Service. Topic No. 560, Additional Medicare Tax If you live in a state with an income tax, state withholding comes out too, using either a flat supplemental rate or standard withholding tables depending on the state. Nine states have no state income tax at all. Add it all up and the share of your vest that gets sold usually lands somewhere between 25% and 40%.
Why the Withholding Often Falls Short
This is the piece most employees miss. The flat 22% federal withholding is an administrative default, not an estimate of what you actually owe. If your total income for the year puts you in the 32% or 35% bracket, every dollar of equity income was underwithheld by 10 to 13 percentage points. A $100,000 RSU vest can leave you with an unexpected $10,000 to $13,000 balance due at filing time.1Internal Revenue Service. Publication 15 (2026), (Circular E), Employer’s Tax Guide
The 2026 brackets show how easily this happens. The 32% bracket starts at $201,775 for single filers, and 35% starts at $256,225.5Internal Revenue Service. IRS Releases Tax Inflation Adjustments for Tax Year 2026 Employees with meaningful equity often sit in that zone, and a single large vest can push you higher.
To avoid an underpayment penalty, your total withholding and estimated payments for the year should cover at least 90% of your current-year liability, or 100% of what you owed last year, whichever is smaller. If the flat rate clearly won’t get you there, quarterly estimated payments can close the gap.6Internal Revenue Service. Estimated Taxes
What Happens to the Shares You Keep
Once the sell to cover clears, the net shares are yours. Your cost basis in them equals the fair market value on the vesting date, which is the price the IRS treats as your purchase price for any future gain or loss. If your shares vested at $100 and you later sell at $130, the gain is $30 per share.
How that gain is taxed depends on how long you hold. Sell within a year of vesting and the profit is short-term, taxed at ordinary income rates. Hold more than a year and it qualifies for long-term capital gains rates of 0%, 15%, or 20%, depending on income.7Internal Revenue Service. Instructions for Form 8949
When you sell, the transaction goes on Form 8949 and flows to Schedule D. Your brokerage sends a 1099-B showing the proceeds. Watch this closely: the 1099-B sometimes reports a cost basis of zero or an incorrect figure because the broker doesn’t always account for the income you already recognized at vesting. If you don’t correct the basis on Form 8949, you’ll be taxed twice on the same money. Check every 1099-B against your vesting records.
How Sell to Cover Compares to Your Other Choices
Most equity plans give you at least two other withholding options, and knowing what they do makes the sell to cover choice a real one instead of a default.
- Same-day sale (sell all). The broker sells every vesting share and hands you the cash left after taxes and fees. Maximum liquidity, no future stock price risk, and no upside if the stock keeps climbing.
- Hold all (pay cash for taxes). You keep every share and write a check or authorize a payroll deduction for the tax bill. Maximum equity position, but you need liquid cash equal to the full withholding, which on a large vest can run tens of thousands.
- Sell to cover. The middle path. You keep most of the shares and don’t need any personal cash, but you’re still holding concentrated stock in one company and you get less immediate liquidity than a full sale.
For employees who want to stay invested in the company but don’t have cash sitting around for tax day, sell to cover is usually the practical pick. It’s also the default at many companies, which means it’s what happens if you never make an active election.
Setup and Execution Risk
The administrative side needs attention well before the vest. Log into your company’s equity plan platform (commonly Fidelity, Charles Schwab, or Morgan Stanley at Work), select sell to cover as your withholding election, and sign the grant agreement for each award. Confirm your brokerage profile has accurate personal information and a valid tax ID, because payroll uses it to calculate the right federal and state withholding for your location and filing status. If any of this is missing, some plans will fall back to a cash-transfer requirement or delay the release of your shares.
On vest day, the broker uses a market order, so you don’t control the execution price. If the stock gaps down at the open or moves sharply in the first minutes, the price you receive can come in below what the tax calculation assumed, and the broker may sell a few extra shares to make up the shortfall. In volatile markets that slippage can meaningfully cut into your net share count. There’s no clean way to hedge it, since the order is automated and tied to the vest date, but knowing it exists helps you set realistic expectations for what will land in your account.
Watch for Wash Sales if You Have Regular Vests
If you sell company stock at a loss within 30 days before or after acquiring substantially identical shares, the IRS disallows the loss under the wash sale rule.8Office of the Law Revision Counsel. 26 USC 1091 – Loss From Wash Sales of Stock or Securities A new RSU vest counts as an acquisition of the same stock, so employees on a quarterly vest schedule can easily trigger this by selling losing shares near a vest date.
The disallowed loss isn’t erased. It gets added to the cost basis of the replacement shares and comes back to you when you eventually sell those. But the timing mismatch causes real confusion at tax time, especially when the broker doesn’t flag the wash sale on the 1099-B. If you have vests coming every quarter, factor that 61-day window in before selling any shares at a loss.