Tax · super (composes 4 primitives)
Equity comp master
Type the grant, strike, FMV, and sale price. We chain ISO AMT exposure (or NQSO ordinary income at exercise), QSBS eligibility (5-yr hold, $10M exclusion), 83(b) election impact for early-exercise, and net after-tax proceeds at sale.
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Inputs
Result
Net after-tax proceeds: $234,850 on $305,000 gain (23.0% effective tax).
Confirmed math: 23.0% blended tax rate. Compare against alternative scenarios (early-exercise + 83(b), tranched sale, donor-advised fund).
- 1
Cost to exercise
$15,000
10,000 shares × $1.50 strike
- 2
Bargain element at exercise / vest
$70,000
(FMV $8.50 − strike $1.50) × shares
- 3
AMT at exercise
$0
28% AMT on bargain element above $85,700 exemption
- 4
Gross sale proceeds
$320,000
10,000 × $32.00
- 5
QSBS exclusion
Not eligible
Requires C-corp + ≤$50M assets at issuance + 5-yr hold
- 6
LTCG tax at sale
$70,150
23% on $305,000 taxable gain
- 7
Net after-tax proceeds
$234,850
Sale − exercise cost − exercise tax − sale tax
Assumptions & notes
- AMT calculation here is simplified — real AMT uses an alternative income calculation including state tax addback, a 26%/28% tier, and exemption phaseouts.
- QSBS requires the corporation to be a C-corp with ≤$50M of assets at issuance and active in a qualifying trade.
- Federal LTCG of 20% kicks in above $518k single / $583k MFJ taxable income; 0% bracket up to $47k single. Net Investment Income Tax adds 3.8% above $200k single / $250k MFJ.
Multi-scenario comparison
What if — ±20% on one input
| Scenario | Number of shares / units | Headline | Δ vs baseline | Magnitude |
|---|---|---|---|---|
| −20% (cautious) | 8,000 | Net after-tax proceeds: $187,880 on $244,000 gain (23.0% effective tax). | $-3,000 | |
| Baseline | 10,000 | Net after-tax proceeds: $234,850 on $305,000 gain (23.0% effective tax). | 0 | |
| +20% (aggressive) | 12,000 | Net after-tax proceeds: $281,820 on $366,000 gain (23.0% effective tax). | +$3,000 |
Try the input with the highest sensitivity (above). The Δ column shows the dollar swing from a 20% move — that's how much room you have for a counter, raise, or hedge.
Goal seek
Solve for an input value
Pick the input you want to vary and the output you care about. We'll find the input value that gets you to the target. Bisection-based; converges in < 50 iterations.
Monte Carlo simulation
Distribution under input uncertainty (500 trials)
We perturb every numeric input with normal-distributed noise (10–25% sigma depending on input type) and run 500 compute trials. The output is a probability distribution, not a single number — closer to how finance actually works.
Most-leveraged inputs (sensitivity analysis)
Where to focus — what moves the answer most
Each input perturbed ±10%; measured impact on Cost to exercise. Higher elasticity = bigger lever.
- 1
Number of shares / units
Elasticity ↑ 1.00× — 10% change in this input increases Cost to exercise by 10.0%.
- 2
Strike price (per share)
Elasticity ↑ 1.00× — 10% change in this input increases Cost to exercise by 10.0%.
- 3
FMV at exercise / vest
Elasticity ↕ 0.00× — 10% change in this input affects Cost to exercise by 0.0%.
- 4
Sale price per share
Elasticity ↕ 0.00× — 10% change in this input affects Cost to exercise by 0.0%.
ShowMath is the only calc site that surfaces this. Adjust the highest-leverage input first — that's where small moves create big results.
Chain payload (for the 3D constellation)
{
"slug": "equity-comp-master",
"depth": 1,
"primitives": [
"iso-amt-calculator",
"rsu-vesting-calculator",
"qsbs-exclusion-calculator",
"eighty-three-b-election"
],
"composes": [],
"chain": [
{
"key": "exercise_cost",
"label": "Cost to exercise",
"numeric": 15000
},
{
"key": "bargain_element",
"label": "Bargain element at exercise / vest",
"primitive": "rsu-vesting-calculator",
"numeric": 70000
},
{
"key": "exercise_tax",
"label": "AMT at exercise",
"primitive": "iso-amt-calculator",
"numeric": 0
},
{
"key": "sale_proceeds",
"label": "Gross sale proceeds",
"numeric": 320000
},
{
"key": "qsbs",
"label": "QSBS exclusion",
"primitive": "qsbs-exclusion-calculator",
"numeric": 0
},
{
"key": "sale_tax",
"label": "LTCG tax at sale",
"numeric": 70150
},
{
"key": "net_proceeds",
"label": "Net after-tax proceeds",
"numeric": 234850
}
]
}The chain explained
Each step above corresponds to a primitive calculator. Click any to see the stand-alone version with its own explainer + sources.
- iso amt calculatorshipping soon
- rsu vesting calculatorshipping soon
- qsbs exclusion calculatorshipping soon
- eighty three b electionshipping soon
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