A vesting cliff is a period at the start of a vesting schedule during which no equity is earned. If a founder leaves before the cliff is reached, they leave with nothing.
The most common cliff is one year.
Why a cliff exists
The cliff protects the company from a founder who commits, receives an equity promise, then leaves within months. Without a cliff, even monthly vesting would hand a departing founder a slice of equity for a few weeks of work. The cliff sets a minimum commitment: prove you are here for at least a year, or earn nothing.
At the one-year mark, the cliff portion vests all at once. On a four-year schedule, reaching the one-year cliff typically vests 25% of the founder's total equity in a single step. After that, the remaining equity vests gradually, usually monthly.
The cliff is the team's protection against a founder who leaves before they have truly started.
What happens if you leave one day before the cliff?
You earn nothing. This is the entire point of the cliff. A founder who leaves at month eleven has earned zero equity, while a founder who stays to month twelve earns a full quarter of their stake. It is a deliberately sharp line.