Interactive QSBS Calculator (Section 1202)

Estimate your federal + state taxes, effective rates, baseline QSBS tax savings, and the additional potential savings from QSBS stacking strategies. Simple Mode

1) Sale + Cost Basis

Portion of the deal you personally receive for stock. Options/wages not modeled here.
Used for the "10× basis" QSBS cap test (simplified; pro-rata basis allocation).

2) Long-Term vs Short-Term Split

Total shares
0
Implied price/share
—

3) QSBS Inputs

Must be ≤ long-term shares. Calculator uses this to estimate QSBS-eligible gain.
For QSBS, timing is based on original issuance rules. Post-2025 QSBS tiers in this calculator apply to stock issued after July 4, 2025.
Defaults to today.

4) QSBS Stacking Scenario (planning lens)

1 = standard single taxpayer cap.
2+ approximates advanced strategies (family gifting, trust structures, entity planning) that may create additional QSBS "caps" (highly fact-specific).
Assume enough caps to cover all above-cap QSBS gain
When enabled, the calculator assumes the entire above-cap QSBS gain could qualify (best-case, simplified).
Applies only to the incremental stacking portion. Your Base Case "Final State Tax Owed" remains based on your state inputs. Example: separate nongrantor trusts administered in a no-state-tax jurisdiction may reduce state tax on the trust-level gain, depending on state rules and facts.
Even if stacking is off, the calculator still shows a maximum stacking opportunity ceiling when QSBS applies. i
If your QSBS cap is driven by 10× basis, incremental stacking may be overstated in simplified models because basis may be divided among additional taxpayers/trusts. This calculator applies a conservative assumption for the incremental caps when basis is the binding constraint (see Results notes).

5) State Tax (optional)

Example: NY = generally conforming; CA = does not conform.
Modeled as an added % on the same base as capital gains.

Results

Ready
QSBS Stacking Opportunity (Incremental) i
Modeled: Off
Maximum additional stacking savings (ceiling)
$0
Modeled additional stacking savings (your selections)
$0
Above-cap QSBS gain coverage
0.0%
—
"Ceiling" assumes enough additional QSBS caps exist to cover all above-cap QSBS gain. "Modeled" applies your selected multiplier/MAX and state lens (incremental portion only).

How to interpret stacking outputs i

  • Base Case: taxes under your current inputs (no extra taxpayers assumed).
  • Ceiling: maximum incremental savings if all above-cap QSBS gain could be sheltered (best-case).
  • Modeled: incremental savings based on your selected multiplier/MAX and state lens.
  • Stacked Scenario: Base Case adjusted by the Modeled incremental savings.
QSBS Tax Savings
—
Baseline QSBS savings (federal)
$0
Compared to the same scenario with no QSBS exclusion.
Baseline QSBS savings (state)
$0
Depends on state conformity selection.
QSBS stacking potential (modeled)
$0
Illustrative incremental savings if additional QSBS "caps" are available (based on your selections).

QSBS Stacking Potential i

Gains above your standard QSBS cap (modeled)$0
Additional gain that could qualify with stacking (modeled)$0
Potential additional federal tax savings (modeled)$0
Potential additional state tax savings (state lens)$0
LT gain (modeled)
$0
ST gain (modeled)
$0
Base Case (Current Inputs)
BASE
Gross Deal Value$0
Final Federal Tax Owed$0
Effective Federal Rate0.0%
Final State Tax Owed$0
Effective State Rate0.0%
Total Tax Owed$0
Net Proceeds After Tax$0
Effective Total Tax Rate0.0%
With QSBS Stacking Implemented (Illustrative) i
STACKED
Gross Deal Value$0
Final Federal Tax Owed$0
Effective Federal Rate0.0%
Final State Tax Owed$0
Includes the modeled state-lens impact on the incremental stacking portion only. Base Case state tax remains based on your entered state inputs.
Effective State Rate0.0%
Total Tax Owed$0
Net Proceeds After Tax$0
Effective Total Tax Rate0.0%
Federal LT vs ST splitHidden
QSBS excluded amountHidden
QSBS above cap (taxed)Hidden
AMT / NIIT componentsHidden
State base & surtax calcHidden
Get the Founder QSBS Playbook See how we optimize QSBS
Advanced modeling (trust stacking, multi-entity structures, state residency strategy, §1045 rollovers, charitable planning, deal levers, etc.) is addressed in founder planning sessions.

Important disclaimers & assumptions i

Planning tool only (not tax advice)

This calculator is a simplified planning tool for educational purposes and does not provide tax, legal, or accounting advice. Results may differ materially from actual tax outcomes.

Simplified modeling assumptions

  • Proceeds and basis are allocated pro-rata by share counts; actual basis and lot-level tax treatment can differ.
  • Federal rates are simplified and assume the top federal rates apply (LT = 23.8%, ST = 40.8%); the calculator does not model brackets, phaseouts, deductions, AMT calculations, NIIT thresholds, or filing status.
  • QSBS rules are simplified to reflect holding periods and exclusion percentages; actual QSBS eligibility depends on issuer qualification, original issuance rules, redemptions, active business requirements, and other factors.
  • Legacy QSBS includes an AMT preference proxy; actual AMT impact may be 0 or different depending on the taxpayer.
  • If your QSBS cap is driven by 10× basis, incremental "stacking" may not scale proportionally because basis may be divided among additional taxpayers/trusts; this calculator applies a conservative assumption for incremental caps when basis is the binding constraint.

QSBS stacking is highly fact-specific

"Stacking" outputs illustrate potential incremental savings if additional QSBS "caps" are available through structures such as family transfers and nongrantor trusts. Whether stacking works depends on legal ownership, timing, gift/transfer rules, holding periods, trust design, and federal/state tax law.

State planning lens applies only to the incremental portion

The "State planning lens" models potential state-tax treatment for the incremental stacking portion (e.g., trust-level taxation) and may not reflect your personal state residency or sourcing rules. State outcomes depend on state law, trust residency rules, sourcing rules, administration, and other facts.

Verify with a qualified advisor

Before acting, consult your tax advisor regarding your specific facts and applicable federal/state rules.

QSBS Basis Disclaimer

For Qualified Small Business Stock (QSBS) purposes, the tax basis used to determine the QSBS exclusion limit may differ from the basis used to calculate taxable capital gain on a sale.In certain situations, including LLC-to-C-corporation conversions, reorganizations, or other restructuring events, a shareholder may have a stepped-up or carryover basis for QSBS exclusion purposes while still recognizing taxable capital gain up to the amount of their economic or historical basis at the time of sale. As a result, even if stock otherwise qualifies for a full QSBS exclusion and the calculator reflects "zero tax", a portion of the sale proceeds may still be subject to capital gains tax. This commonly occurs when a business converts to a C-corporation at a meaningful valuation and is later sold after satisfying the QSBS holding period. This calculator does not model basis mismatches, conversion-related gain, or transaction-specific tax attributes. Actual tax outcomes depend on detailed facts and should be reviewed with qualified tax counsel or a CPA.