QSBS Exclusion Calculator

How the calculator works

The calculator applies two regimes based on when you acquired your stock:

• Pre-OBBBA (before July 4, 2025): You need a full 5-year holding period for 100% exclusion. The cap is the greater of $10 million or 10× your cost basis per issuer. If you haven't held 5 years, the federal exclusion is zero — though a §1045 rollover may defer gain into replacement QSBS.
• Post-OBBBA (on or after July 4, 2025): The One Big Beautiful Bill Act introduced a tiered exclusion: 50% at 3 years, 75% at 4 years, 100% at 5 years. The cap increased to the greater of $15 million or 10× your basis. There is no AMT preference item for any tier. The gross assets threshold at issuance also increased from $50M to $75M.¹

The state rate is applied to the full gain in all cases. This reflects the planning reality: CA, PA, AL, and MS do not conform to §1202, so state tax is owed on the entire gain even when the federal gain is fully excluded.

The eligible percent field lets you model situations where only a portion of shares likely qualifies — for example, if some lots were issued when the company had already crossed the gross assets threshold, or if you are uncertain about a subset of shares.

What the calculator does not capture

• Gifting and stacking: You can gift QSBS to family members before a sale, with each donee using their own $15M cap. A co-founder with $200K basis and three family members could potentially exclude $60M+ combined. See the gifting and stacking guide.
• State residency planning: Moving from CA to a conforming state before a sale eliminates state QSBS tax. This is complex (FTB part-year rules, clawback risk) but can be worth hundreds of thousands of dollars. See California QSBS guide.
• §1045 rollover: If you sell before 5 years (pre-OBBBA stock) or before reaching 3 years (post-OBBBA), you may reinvest proceeds in replacement QSBS within 60 days and carry the original holding period. See the §1045 rollover guide.
• Charitable structures: Donating a portion of QSBS to a DAF before LOI avoids both the federal gain (QSBS excluded) and the charitable deduction limit on appreciated stock. See the charitable planning guide.
• Multi-lot complexity: If you have shares issued at different dates (some qualifying, some not — e.g., post-Series B when gross assets exceeded the threshold), lot-by-lot analysis matters. Your advisor and CPA will need your cap table and issuance documents.