What is an 83b election?

Generally, when someone acquires stock in a company that is subject to vesting, each vesting period results in a tax event such that the person has to pay taxes on the gains in the stock over what that person paid for the stock. For stock that vests monthly, this would mean that taxes would have to be paid out-of-pocket every month on these "paper" gains, even though the stock didn't change hands and the person didn't receive any cash at the time of vesting. Generally, if the person files an 83b election within 30 days of purchasing/acquiring the stock, the individual would be taxed all at once at the beginning on any gains over what that person paid for the stock (in most cases these gains are $0 because of the minimal time lapse) rather than at each vesting event. PLEASE CONSULT YOUR LEGAL/TAX ADVISORS FOR ADVICE.