Early exercise and the 83(b) election
Early exercising without filing an 83(b) is usually worse than not exercising at all.
Why they pair
Early-exercised shares are unvested restricted stock. Without the election, each vesting tranche is a taxable event at the then-current value.
For ISOs
The election also fixes the AMT measurement date at exercise, when the spread is smallest.
The checklist
Exercise, pay for the shares, file the 83(b) within 30 days by certified mail, notify your employer, and store the receipt with your tax records permanently.
This article is educational and not tax, legal, or financial advice. Talk to a CPA or tax advisor about your specific situation.