How an ESPP works
You enroll before an offering period starts and choose how much to contribute, usually a percentage of each paycheck up to a cap the plan sets. The money comes out of your after-tax pay and builds up in the plan. On each purchase date, the plan uses the accumulated cash to buy shares at the plan price and deposits them in an account with the plan’s broker.
Two features create the value. The discount lets you buy below market, and a qualified plan can set the price as low as 85% of market value. A lookback applies that discount to the lower of the price on the first day of the offering and the price on the purchase date. When the stock rises during the offering, the lookback can make your effective discount much larger than 15%.
Unlike RSUs or stock options, an ESPP isn’t a grant. You spend your own money, and the shares are fully yours the moment they are bought, with no vesting schedule. That makes it closer to a discounted purchase program than to a retention tool.
Section 423 rules and limits
Many ESPPs are qualified plans under section 423, which earns the tax treatment described below in exchange for a set of rules. A plan that breaks them is a nonqualified ESPP, and the discount is then generally taxed as wages when you buy, the same way other stock received for work is taxed. Your plan document and prospectus show which choices your employer made within these limits. The main section 423 requirements:
- Price floor: the purchase price can’t be less than 85% of the lower of the market value at the offering start and at purchase.
- Purchase limit: no more than $25,000 of stock per calendar year, valued at the price on the offering start date.
- Offering length: up to 27 months, or up to 5 years if the price is always at least 85% of the purchase-date value.
- Eligibility: generally all employees, though a plan may exclude those with under 2 years of service, part-time or seasonal staff, and highly compensated employees.
- Owners: anyone owning 5% or more of the company’s voting power or stock value can’t participate.
- Employment: you must be an employee from the grant date until 3 months before each purchase.
Sell right away or hold for a qualifying sale?
With a 15% discount, buying at $85 and selling at $100 is a 17.6% gain on the money you put in (15 ÷ 85), before tax, earned in a few months. Selling as soon as shares arrive locks that in with little market risk. It is a disqualifying disposition, so the whole spread is ordinary income.
Holding for a qualifying disposition changes only part of the tax. The discount measured at the offering start stays ordinary income either way, so the saving is limited to moving the rest of the gain from your marginal tax rate to long-term capital gains rates. To earn it, you keep the shares for up to two years, exposed to one company’s price, often the same company that pays your salary and your equity grants.
A price drop can erase the saving quickly. After a disqualifying sale at a loss, you still owe ordinary income on the purchase-date spread, while the loss is a capital loss that offsets capital gains and only $3,000 of other income a year ($1,500 if married filing separately), with the rest carried forward. Selling promptly and reinvesting in a diversified portfolio limits that risk; how much to hold depends on how much of your wealth already rides on your employer.
Common ESPP mistakes
An ESPP is easy to join and easy to mishandle at tax time. The costliest errors are about reporting and concentration rather than about whether to enroll. Review them when you first sign up and again each time you sell, because the tax result of a sale depends on offering and purchase dates that are easy to lose track of across several purchase periods. Keep every Form 3922 with your records.
- Reporting the Form 1099-B basis unchanged, which taxes the discount twice.
- Assuming a qualifying sale means no ordinary income. Unless you sell at a loss, part of the gain, up to the offering-start discount, is still ordinary income.
- Joining without room in the budget. Contributions come back as shares within months, but your paychecks are smaller until then.
- Letting purchases pile up in one stock alongside RSUs and a 401(k) that may hold company shares.
- Forgetting that shares sold within a year of purchase add short-term gains on top of the ordinary income.
Illustrative numbers
One lookback purchase, sold two ways
- 85%
- the lowest price section 423 allows, a 15% discount
- price at offering start
- the market price on the grant date, used by plans with a lookback
- price on purchase date
- the market price on the day the plan buys shares
Your plan may offer a smaller discount or no lookback; its document sets the actual terms.
Price at offering start$40
Price on purchase date$50
Your purchase price (85% of $40)$34
Shares bought with $6,800 of contributions200
Disqualifying sale at $60: ordinary income / capital gain$3,200 / $2,000
Qualifying sale at $60: ordinary income / long-term gain$1,200 / $4,000
The same $5,200 profit is taxed two ways. A qualifying sale keeps only the $6-a-share offering-start discount, $1,200, as ordinary income and moves $2,000 more into long-term gain. It requires holding the shares more than two years from the offering start and one year from purchase.
At a glance
Qualifying vs. disqualifying ESPP sales (qualified section 423 plan)
| Question | Qualifying disposition | Disqualifying disposition |
|---|---|---|
| When it happens | More than 2 years after offering start and 1 year after purchase | Any earlier sale |
| Ordinary income | Lesser of the offering-start discount or the actual gain | Purchase-date price minus purchase price |
| Ordinary income after a price drop | None if sold at a loss | Still the full purchase-date spread |
| Rest of the gain or loss | Long-term capital gain or loss | Short- or long-term by holding after purchase |
| Social Security and Medicare tax | None | None |
Put it in your plan
ESPP in MoneyWhatIf
To model ESPP shares you already own, enter them in MoneyWhatIf as a brokerage account with their balance and cost basis. When the plan later sells from that account, it treats a proportional slice of basis as returned and taxes the rest as long-term capital gain stacked on your other income. The model doesn’t select tax lots or distinguish every short-term holding, and every modeled gain uses long-term rates, so the ordinary-income part of an ESPP sale isn’t captured.
Common questions
ESPP FAQs
Is an ESPP worth it?
For many employees the math is favorable: a 15% discount returns about 17.6% on the money contributed if you sell at purchase, and a lookback can add more. The costs are smaller paychecks while you contribute, tax on the discount, and price risk for as long as you hold. It is less attractive if you can’t spare the cash or already hold a large stake in your employer.
What is the ESPP holding period?
For a qualifying disposition, you must sell more than 2 years after the offering (grant) date and more than 1 year after the purchase date; both clocks must be met. Separately, your capital gains holding period starts the day after each purchase, and it decides whether any gain beyond the ordinary income is short-term or long-term.
Are ESPP contributions pre-tax?
No. Contributions come out of pay that has already been taxed, so unlike traditional 401(k) deferrals they don’t lower the wages on your W-2. What a qualified plan defers is the tax on the discount: nothing is due when shares are bought, and the discount becomes ordinary income, free of Social Security and Medicare tax, only when you sell. Employers aren’t required to withhold on that income, so you may need to raise withholding or make estimated tax payments in the year you sell.
How much can I buy through an ESPP each year?
Section 423 caps purchases at $25,000 of stock per calendar year, measured at the market price on the offering start date, not the discounted price you pay. With a $40 starting price, that is 625 shares a year. Your plan may set a lower cap, such as a maximum percentage of pay or a share limit per purchase.
What happens to my ESPP if I leave my company?
Shares already bought are yours, and the clocks for a qualifying disposition keep running after you leave. For a purchase to receive section 423 treatment, you must have been an employee within 3 months before it, so leaving generally ends your participation. Your plan document says what happens to contributions not yet used for a purchase.