This may be country-specific, but can options be put in tax-free accounts like TFSAs (Canada), (N)ISAs (UK), or (I think) IRAs (US)? Wouldn't that mitigate the capital gains tax issues?
In the US, with enough foresight, they can be purchased through a Roth IRA, which would prevent any tax from being applied. The (major) caveats are three-fold:
1) The money cannot be touched until retirement. So… if it turns out to be Uber and worth hundreds of millions, you can't touch any of it! It's probably a good idea to only put 25-50% of your stock in the account.
2) You can only contribute a tiny amount yearly to an IRA ($6k I think). So, the options strike price must be dirt-cheap for this to make sense.
3) Actually doing it is quite complex, and requires a third-party account custodian. If you're accepting a random startup offer pre-funding (the only time you'd have essentially free options, allowing #2 above not to be an issue), you're unlikely to go through that trouble.
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The huge benefit, however, is that if you do succeed in hitting in big with something that way, you'll have a gigantic Roth IRA balance, tax-free, and you'll be able to use it to make other investments, whose cost basis and profits will all be tax-free.
