Secondary Sale Calculator for Founders
Pressure-Test Your Secondary Decision.
When founders Google “should I take a secondary or hold to exit,” they’re usually not asking about price.
They’re asking:
- How much cash do I actually keep if I sell now, after tax?
- What am I really giving up if I hold, and what return am I implicitly betting on?
- How much does QSBS, timing, basis, and state tax change the answer?
- If I sell, what happens if I reinvest and diversify until exit?
- How much should I take off the table?
- Is there a better solution than taking a secondary, such as a structured secondary, where I still retain upside?
This secondary sale calculator is built to answer that decision, in after-tax dollars, using the same block of shares in both scenarios.
KEYSTONE RECOGNITION
What This Secondary Sale Calculator Compares
This tool models two paths for the same block of equity:
Scenario A: Sell a block in a secondary today
- Shows your after-tax cash today, taking into account QSBS
- Optionally grows those after-tax proceeds to exit if you choose to reinvest
Scenario B: Hold that same block to exit
- Shows your after-tax value at exit
- Applies QSBS timing and caps at a high level, based on your inputs
The output is a clean, side-by-side comparison that makes the tradeoff explicit.
What You Need to Get a Result (Two Numbers)
You can run the model with just two inputs:
1: Block value today
The dollar value of the shares you could sell now.
2: Base-case exit value for that same block
What you think that block is worth at exit, not your entire company stake.
Everything else improves accuracy, but these two numbers turn the model on.
Why QSBS Is Treated as “Yes / No / Not Sure”
Most founders fall into one of two traps:
- They assume QSBS applies when it doesn’t
- Or they ignore QSBS entirely because they are unsure
If you select “Not sure (show both)”, the calculator shows a range for the hold scenario, so you can see how much QSBS eligibility actually matters before making a decision.
If QSBS changes the outcome by seven figures, it’s worth validating before signing anything.
The Variables That Usually Change the Answer
You can get a quick answer with minimal inputs, but these factors typically swing the result the most:
| QSBS eligibility and timing | Tax basis for the block | State tax treatment | Time to exit | What you do with proceeds if you sell |
|---|---|---|---|---|
|
Being early or late by months can change whether an exclusion applies, and by how much. |
Option exercises, conversions, and multiple grants often make basis more complex than founders expect. |
Conforming vs non-conforming states, or planning a move, can materially change net proceeds. |
Time is the hidden cost of holding. A longer exit timeline lowers the implied return fast. |
Selling isn’t just “giving up upside.” If you sell, diversify, and reinvest, the sell path can compound meaningfully. |
How to Use This Tool (Recommended)
- Enter your block value today and base-case exit value
- Choose QSBS: yes, no, or not sure
- Add dates if you know them (acquisition, secondary, exit date estimate)
- Add basis and select a state tax preset
- Turn on reinvestment if you want a realistic sell comparison
- Use the exit multiple slider to pressure-test optimism and downside
You will walk away with a clear takeaway:
How much after-tax value holding adds (or costs), and what has to go right for that decision to make sense.
What This Tool Does, and Does Not Do
This secondary sale calculator is a decision-support tool, built for clarity and speed.
This calculator does:
- Estimate after-tax proceeds from a secondary sale
- Estimate after-tax value at exit if you hold
- Model QSBS timing tiers and a single-taxpayer, single-issuer cap (as described in the tool)
- Apply simple state-tax presets
- Show the impact of reinvesting secondary proceeds
- Make the implicit after-tax IRR of holding visible
This calculator does not:
- Model QSBS stacking, multi-taxpayer strategies, or tranche-level complexity
- Model state residency audit risk or partial-year moves
- Replace tax or legal advice
When a Calculator Isn’t Enough
You should go deeper if any of these are true:
- The outcome swings materially based on QSBS on vs off
- You have multiple grant dates, conversions, or complex basis history
- You’re planning a state move around liquidity
- You want cash without fully selling (structured or partial liquidity)
- You’re exploring ways to preserve upside while reducing concentration
Keystone works with venture-backed founders navigating exactly these scenarios. If the difference between selling and holding is meaningful, validating the assumptions matters.
If you are a venture-backed founder considering a secondary sale or tender offer, and your expected personal exit value (in aggregate) is meaningful, this secondary sale calculator is only the first step.
We work with founders at exactly this moment to:
- Validate QSBS eligibility and timing before a decision becomes irreversible
- Confirm basis and state tax assumptions that often swing outcomes by seven figures
- Pressure-test “sell vs hold” under multiple exit and timing scenarios, not just a single base case
- Evaluate structured liquidity alternatives that can deliver cash today while preserving upside, such as a structured secondary
Founders usually reach out when the math is close, QSBS is uncertain, or the cost of getting it wrong is high.
If that’s you, we can take what you’ve modeled here and turn it into a defensible, decision-ready plan.
to pressure-test this decision before you sign anything.
Important DisclaimersThis calculator and information are for educational and illustrative purposes only and do not constitute tax, legal, or financial advice. Calculations involve complex federal and state rules that vary based on individual circumstances. Tax calculations and QSBS rules are complex and subject to specific requirements and limitations. Consult with qualified tax and legal professionals regarding your specific situation.
