Case study: catching the ESPP double-tax before filing

One filer almost paid tax twice on the same discount. The fix was one number on one form, and it saved him about $4,000.

ESPPs · Case studies

How does a careful person nearly pay tax twice on the same dollars and never notice? The numbers on the form look reasonable. They are just wrong in the IRS’s favor. Here is one filer who caught it the night before he hit submit, fixed one figure, and kept about $4,000 he was about to hand over for no reason.

Call him Dev, a product manager at a public company with a standard ESPP. He bought through it all year, sold a batch of shares, and sat down to file with a tax program and his 1099-B. (Composite, identity changed.)

What the 1099-B told him

Dev’s plan let him buy at a discount. Over the year he bought shares worth about $30,000 at market, for which he paid roughly $25,500 after the discount. He sold the batch for $31,000.

The 1099-B from his broker showed a cost basis of $25,500, the price he paid. So the program computed a capital gain of $5,500, the full distance from what he paid to what he sold for. Dev almost accepted it. The math added up.

The basis was right on paper and wrong in fact

The broker reported only the discounted price Dev paid. It left out the discount that had already been taxed as ordinary income on his W-2. A basis that is too low makes the gain too high, and the discount gets taxed a second time as capital gain.

What he was missing

The piece the 1099-B ignored was the discount that already ran through his paycheck as income. When ESPP shares are sold, part of the gain is ordinary income, and that amount is added to your basis because you already paid tax on it. For Dev’s sale, that ordinary-income piece was the roughly $4,500 gap between what he paid and the market value when he bought.

The basis the broker reported

$25,500, the discounted price Dev actually paid. Subtract that from the $31,000 sale and the program saw a $5,500 capital gain. Most of that “gain” was his discount, which the W-2 had already taxed once.

The basis after the fix

$25,500 paid plus the roughly $4,500 of discount already taxed as income, so about $30,000. Subtract that from the $31,000 sale and the real capital gain is about $1,000. The discount is taxed once, not twice.

By correcting the basis, Dev shrank his reported capital gain from about $5,500 to about $1,000. He was about to be taxed twice on roughly $4,500 of discount. At his rate, fixing it kept him from overpaying by something in the neighborhood of $4,000.

The dollar saved depends on your rate

The exact tax Dev saved depends on his capital gains rate, which turns on his income and how long he held the shares. The share prices here are an illustrative composite to show the mechanics, not rates or limits to rely on.

How he fixed it

The repair was small and it lived on one form.

The one move that saved the money

Dev pulled his Form 3922, found the discount already taxed as income, and reported the correction on Form 8949: he kept the broker’s basis, then used the adjustment column and the right code to add back the ordinary-income piece. His capital gain dropped to the correct, smaller number, and the double tax was gone.

The whole thing took twenty minutes once he knew what to look for. The hard part was not the fix. It was knowing the basis was wrong in the first place, because nothing on the form waved a flag.

What this means for you

The ESPP discount is only as good as the basis you report. Before you file, pull Form 3922, find the income already taxed, and add it back on Form 8949. For the step-by-step, read the ESPP cost basis adjustment, and for the full reporting flow, ESPP reporting with Form 3922 and Form 8949. If you have sold ESPP shares in past years and never made this adjustment, you may have overpaid, and it may be fixable. Talk it through with me before the next filing season.

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