ESPP After-Tax Calculator

Your Section 423 ESPP has two exit strategies: sell your shares right after purchase (disqualifying disposition) or hold the 2-year/1-year period for qualifying treatment. The tax difference can be significant — or surprisingly small, depending on your marginal rate and state. Enter your plan details below to see the numbers side by side.

How the two strategies differ

Sell immediately (disqualifying disposition)

When you sell within 2 years of the offering date or within 1 year of the purchase date, your employer reports the full spread between your purchase price and the market price at purchase on your W-2 as ordinary income. You owe tax at your marginal rate. Any gain or loss after the purchase date is a capital gain or loss (short-term if held less than a year from purchase, long-term if held longer).

The immediate-sell strategy is simple, eliminates single-stock risk, and often produces a competitive after-tax return — especially for high earners in California, where there is no state capital gains preference.

Qualifying disposition: the patient strategy

Hold your shares for both 2+ years from the offering date and 1+ year from the purchase date. At sale, your ordinary income is capped at the lesser of:

• Your actual gain on the shares (sale price minus your purchase price), or
• The discount element at the offering date (offering-date FMV × discount rate)

The rest of your gain — everything above your adjusted basis (purchase price + ordinary income recognized) — is taxed as long-term capital gain. For employees in the 37% bracket, converting even a portion of gain from ordinary income to 15–20% LTCG generates real savings.

The basis trap to avoid when filing

Your brokerage's 1099-B will typically show your cash purchase price as your cost basis — not the adjusted basis that accounts for ordinary income you've already paid. If you sell without adjusting, you'll pay tax on the discount twice. The fix:

• For disqualifying dispositions: adjusted basis = your purchase price + the spread reported on W-2
• For qualifying dispositions: adjusted basis = your purchase price + the ordinary income you report at sale

Keep IRS Form 3922 (issued by your employer for each purchase year) alongside your W-2 and 1099-B when you file. Use these to calculate your correct adjusted basis on Form 8949.

Section 423 annual contribution limit

The IRS caps the FMV of stock you can purchase under a Section 423 ESPP plan at $25,000 per calendar year, measured at the offering-date FMV.¹ This cap is not indexed to inflation. At an offering-date price of $100 with a 15% discount, you can buy approximately $21,250 worth of stock at the discounted price before hitting the ceiling — equivalent to about 250 shares.