An employee stock purchase plan (ESPP) under Section 423 lets you buy company stock at up to a 15% discount with no tax at purchase. You pay tax when you sell. If you sell more than 2 years after the offering date and more than 1 year after the purchase date, it is a qualifying disposition: ordinary income is capped at the discount measured at the offering date, and the rest is long-term capital gain. Sell sooner and it is a disqualifying disposition: the full discount at purchase is ordinary income, even if the price later fell.
How does a Section 423 ESPP work?
You set aside part of each paycheck during an offering period. On each purchase date, the plan buys shares at a discount. Section 423 of the tax code sets the guardrails that make a plan “qualified”:
- Discount: the purchase price can’t be lower than 85% of the stock’s value at the offering date or at the purchase date, whichever the plan uses.
- Lookback: many plans use the lower of the two prices, then apply the discount.
- Annual cap: you can’t accrue the right to buy more than $25,000 of stock per calendar year, valued at the offering date.
- Offering length: up to 27 months, or up to 5 years if the price is based only on the purchase-date value.
With a lookback, the discount can be far more than 15%. If the stock is $40 at the offering date and $50 at purchase, you buy at 85% of $40, or $34. That is a $16 discount against the $50 market price.
When is ESPP stock taxed?
Not at grant and not at purchase. Per Publication 525, you include nothing in income when a statutory option is granted or exercised. The tax event is the sale, gift, or other disposition of the shares.
Your holding period starts the day after the purchase date. What you owe depends on whether the sale meets both holding requirements.
What is a qualifying disposition?
You meet the holding period if you sell after the later of:
- 2 years after the offering (grant) date, and
- 1 year after the purchase (transfer) date.
If you do, Publication 525 says your ordinary income is the lesser of:
- the stock’s value at the offering date minus the option price, figured as if you had bought on the offering date, or
- the sale price minus what you actually paid.
Everything above that is long-term capital gain. If you sell at a loss, there is no ordinary income and the loss is a capital loss.
For an offering that starts January 2, 2026, with a purchase on June 30, 2026, a sale qualifies only after January 2, 2028. The 1-year rule from purchase is met sooner, but the later date controls.
What is a disqualifying disposition?
Any sale before both dates. Your ordinary income is the stock’s value on the purchase date minus the price you paid. Publication 525 is explicit that this amount is not limited to your gain. You add it to your basis, and the difference between that adjusted basis and the sale price is a capital gain or loss, short- or long-term depending on how long you held after purchase.
Worked example: same purchase, three outcomes
Assume a 6-month offering with a 15% discount and a lookback:
- Offering date value: $40. Purchase date value: $50.
- Purchase price: 85% × $40 = $34. You buy 500 shares for $17,000.
- The $25,000 cap is measured at the offering date: 500 × $40 = $20,000, under the limit.
| Scenario | Sale price | Ordinary income | Basis | Capital gain or loss |
|---|---|---|---|---|
| Disqualifying, sold in 3 months | $55 | $8,000 | $25,000 | $2,500 short-term |
| Qualifying | $55 | $3,000 | $20,000 | $7,500 long-term |
| Disqualifying, price fell | $36 | $8,000 | $25,000 | $7,000 short-term loss |
| Qualifying, price fell | $36 | $1,000 | $18,000 | $0 |
How each line works:
- Disqualifying at $55: ($50 − $34) × 500 = $8,000 ordinary. Basis $17,000 + $8,000 = $25,000. Proceeds $27,500.
- Qualifying at $55: the lesser of ($40 − $34) × 500 = $3,000 or ($55 − $34) × 500 = $10,500. Ordinary income is $3,000.
- Disqualifying at $36: still $8,000 ordinary. Proceeds of $18,000 against a $25,000 basis is a $7,000 capital loss. Capital losses beyond your capital gains offset only $3,000 of other income a year ($1,500 if married filing separately), so the ordinary income and the loss may not net out in the same year.
- Qualifying at $36: the lesser of $3,000 or $1,000. Ordinary income is $1,000, with no capital gain.
At $55, assume a 35% ordinary rate and a 15% long-term rate, ignoring state tax and the net investment income tax. The disqualifying sale costs about $3,675 ($10,500 × 35%). The qualifying sale costs about $2,175 ($3,000 × 35% + $7,500 × 15%). The $1,500 difference is what you earn for holding one stock for up to two years.
Why does Form 1099-B overstate your ESPP gain?
Because the broker leaves out the income you already paid tax on. Publication 525 states that for options granted on or after January 1, 2014, the basis on Form 1099-B won’t reflect any amount included in income. It is your job to fix it.
In the disqualifying example at $55, the 1099-B likely shows $27,500 of proceeds and $17,000 of basis, a $10,500 gain. The $8,000 discount is already in box 1 of your W-2. If you file the 1099-B as is, you pay tax on that $8,000 twice.
The fix goes on Form 8949: enter code B in column (f) for an incorrect basis. For a covered sale reported with basis to the IRS, enter the basis shown on the 1099-B in column (e) and a negative $8,000 adjustment in column (g). Your broker’s supplemental statement often shows the adjusted figure; check it against your W-2 rather than assuming the software picked it up.
What is Form 3922?
Form 3922 is the record your employer files for shares transferred to you under a Section 423 plan. The Form 3922 instructions list what it shows:
| Box | What it reports |
|---|---|
| 1 | Offering (grant) date |
| 2 | Purchase (exercise) date |
| 3 | Per-share value, grant date |
| 4 | Per-share value, exercise date |
| 5 | Price paid per share |
| 6 | Shares transferred |
| 7 | Date title first transferred |
| 8 | Price per share if bought at grant |
Every number in the worked example comes from these boxes: box 1 and box 2 set the holding-period dates, boxes 3 and 8 set the qualifying cap, and boxes 4 and 5 set the disqualifying income. You don’t attach Form 3922 to your return. Keep every one until you have sold the shares it covers.
How does ESPP income show up on your W-2?
Your employer reports the ordinary income in box 1 of Form W-2 for the year of sale. Publication 15-B adds two details that matter for cash planning:
- ESPP income is not wages for Social Security or Medicare tax.
- Federal income tax withholding isn’t required on it, whether the sale is qualifying or disqualifying.
So an ESPP sale raises your tax bill without raising your withholding. If your employer doesn’t include the income on your W-2, Publication 525 says you still report it as wages. Check whether box 1 already contains it before you add it again.
Should you sell ESPP shares immediately or hold?
Selling at purchase is a disqualifying disposition. In the example, you would pay ordinary tax on the $8,000 discount and have almost no capital gain. You keep a $16 per share profit on a $34 outlay, which is a 47% return before tax, without carrying the stock.
Holding for a qualifying disposition can lower the tax, but only on the part of the gain above the grant-date discount, and only if the price holds up. A 20% drop in the stock wipes out more than the $1,500 tax saving in the example.
Many ESPP participants already hold company stock in RSUs and options. If your employer’s shares make up a large slice of your net worth, the discount is the reliable part of the deal and the holding period is the risky part. Our guide to a concentrated stock position covers how to size that exposure.
How does ESPP stack with RSUs?
Both land on the same W-2 as ordinary income, but they are withheld differently. RSU income is supplemental wages, so payroll withholds federal income tax on it, often at the 22% supplemental rate, and takes Social Security and Medicare tax. ESPP income has no withholding at all. A year with large RSU vests and an ESPP sale can leave you short in two ways. See RSU tax withholding for the vest side, and RSUs vs stock options for how each award type is taxed.
Before you sell ESPP shares this year:
- Pull Form 3922 for each lot and mark which lots are qualifying.
- Estimate ordinary income for each lot you plan to sell.
- Add it to your RSU income and compare total tax with total withholding.
- Fix the shortfall through a W-4 change or an estimated payment.
- After year-end, check the 1099-B basis against your W-2 and adjust on Form 8949.
To model a sale alongside your other equity, use the stock options calculator. The tech employees page covers how Nino handles RSUs, ESPP, and options together; Nino’s Advisor plans include a CPA and CFP, with federal and state tax filing included; the CPA prepares your return, and nothing is filed until you approve it.