ESPP Calculator

Section 423 Plan Rules

A qualified ESPP is defined by section 423 of the Internal Revenue Code. The limits that shape every purchase:

Nothing is taxed when you buy. Your employer files Form 3922 for each purchase, listing the offering-date price, the purchase-date price and what you paid: the figures you need to report the sale.

Worked Example: Lookback Price, Shares and the Tax Split

1. Purchase price: 85% × the lower of $40 and $50 = $34.00.
2. Shares: $12,500 ÷ $34 = 367.6, so 367 whole shares for $12,478; the $22 left over carries to the next period or is refunded.
3. Disqualifying sale at $55: ordinary income = ($50 − $34) × 367 = $5,872, the bargain element on the purchase date. Capital gain = ($55 − $50) × 367 = $1,835. Tax at 24% on both = $1,849.68.
4. Qualifying sale at $55: ordinary income = the smaller of the actual gain ($21 × 367 = $7,707) and 15% of the offering-date price ($6 × 367 = $2,202), so $2,202. The other $5,505 is long-term gain. Tax at 24% and 15% = $1,354.23.

Your basis for capital gains is the price paid plus the ordinary income: $34 + $16 = $50 a share in the disqualifying case.

Selling Early vs Waiting: Six Outcomes

$12,500 of contributions, 24% ordinary rate, 15% long-term rate.

Waiting for a qualifying sale saves tax only if the price holds. If the stock falls to $30, the quick seller is still taxed on $5,872 of ordinary income but gets a capital loss to offset it; the qualifying seller has no ordinary income at all but a loss on the shares. Without a lookback the discount is just 15% of the purchase-date price, and the gain shrinks with it.

Common ESPP Mistakes

• Paying tax twice on the discount. 1099-B forms often show only the price you paid as basis. Add the ordinary income already on your W-2 (or reported for a qualifying sale) to the basis on Form 8949.
• Assuming qualifying is always better. It lowers the tax on a gain, but a year or more of holding one stock, often your employer, can cost more than the tax saved.
• Miscounting the holding period. Both tests must pass: two years from the offering date, not the purchase date, and one year from purchase.
• Exceeding the $25,000 limit. It is measured at the offering-date price; plans stop deductions or refund excess, so check before raising contributions.
• Forgetting withholding. No tax is withheld on a disqualifying disposition even though the ordinary income lands on your W-2; budget for it.

What This Calculator Does Not Include

It uses the flat rates you enter rather than a bracket calculation, ignores state tax and the 3.8% net investment income tax, and handles one purchase at a time. A capital loss is valued at the rate you enter, as if it offsets other gains; losses beyond your gains offset at most $3,000 of ordinary income a year (IRS Topic 409), with the rest carried forward, so the negative tax figures in the table above are a best case. Plans that reset the offering price when the stock drops, non-qualified (non-423) plans, and sales of shares from several purchases need lot-by-lot records. For a large position, a CPA can match each sale to its Form 3922.

Frequently Asked Questions

How to Use This Calculator

1. Enter your contributions — payroll deductions for the purchase period, from your pay stubs or plan account.
2. Enter the prices — the price at the start of the offering, on the purchase date and when you sell (or expect to).
3. Set the discount and lookback — from your plan document; most qualified plans use 15% with a lookback.
4. Choose when you sell and your tax rates — disqualifying within a year, disqualifying after a year, or qualifying; then your ordinary and long-term capital gains rates.
5. Read the results — purchase price, shares, instant gain, ordinary income, capital gain, estimated tax and what you keep.