Understanding Vesting Schedules: Cliffs, Tranches, and Acceleration

Why Vesting Exists

Companies do not give you all of your equity on day one. Instead, they put it on a vesting schedule — a timeline that releases your equity gradually as you continue working. Vesting exists to align incentives: the company wants to retain you for the long term, and the vesting schedule ensures you earn your equity over time rather than receiving it all upfront and potentially leaving.

Understanding your vesting schedule is essential because it determines when you actually have the right to exercise options and own shares. Until equity vests, it is a promise — not a possession.

The Standard Four-Year Vesting Schedule

The overwhelming majority of startups use a four-year vesting schedule with a one-year cliff:

Year 1: The Cliff

For the first 12 months of employment, none of your equity vests. This period is called the cliff. If you leave the company — for any reason — before your one-year anniversary, you forfeit 100% of your option grant. The cliff protects the company from granting equity to short-term employees.

On your one-year anniversary, 25% of your total grant vests all at once. This is sometimes called "cliff vesting" or "the cliff drop."

Years 2–4: Monthly Vesting

After the cliff, the remaining 75% of your grant vests in equal monthly installments over the next 36 months. Each month, 1/48 of your total grant becomes vested. This continues until the four-year mark, when your entire initial grant is fully vested.

Example

You receive a grant of 48,000 stock options with a four-year vesting schedule and a one-year cliff:

After month 48, all 48,000 options are vested. No additional options vest from this grant after that point (though you may receive refresher grants with their own vesting schedules).

Alternative Vesting Schedules

While the four-year schedule is standard, you may encounter variations:

Three-Year Vesting

Some companies, particularly later-stage startups, use a three-year vesting schedule. The cliff is still typically one year, with the remaining equity vesting monthly over the next two years.

Quarterly Vesting

Instead of monthly vesting after the cliff, some companies vest quarterly — every three months. The total timeline is the same, but the vesting events are less frequent and each tranche is larger.

No-Cliff Vesting

Refresher grants (additional equity awarded after your initial hire grant) often have no cliff, since you have already proven your commitment during the initial cliff period. These grants may vest monthly from day one of the new grant.

Back-Weighted Vesting

Some public companies (notably Amazon) use back-weighted vesting, where a smaller percentage vests in the early years and a larger percentage vests later. For example: 5% in year one, 15% in year two, 40% in year three, and 40% in year four. This heavily incentivizes long-term retention.

The Vesting Commencement Date

Your vesting schedule starts on your vesting commencement date, which is usually your employment start date — not the date the board approves your option grant. This distinction matters because there can be a delay of weeks or months between your start date and the formal board approval.

If your offer letter specifies a vesting commencement date, verify that it matches your start date. Your option agreement will confirm the exact date.

What Happens to Vesting When You Leave

When you leave a company, your vesting stops immediately. You keep all options that have vested up to your last day of employment. All unvested options are typically forfeited and returned to the option pool.

Key nuance: Vested options are not the same as owned shares. After leaving, you must still exercise your vested options within the post-termination exercise period (often 90 days) to convert them into shares. If you do not exercise, the vested options expire.

Severance and Vesting

In some cases, a severance agreement may include continued vesting during a severance period. This is negotiable and depends on the company's policies and your individual agreement. It is more common for executives than for rank-and-file employees.

Acceleration: When Vesting Speeds Up

Certain events can cause unvested equity to vest faster than the standard schedule:

Single-Trigger Acceleration

If your agreement includes single-trigger acceleration, all or a portion of your unvested equity vests immediately upon a change of control (acquisition). The acquisition alone is sufficient — no second event is required.

Double-Trigger Acceleration

The more common form of acceleration. Two events must occur: (1) a change of control, and (2) your involuntary termination within 12–24 months after the deal closes. If both triggers are met, your unvested equity accelerates.

Negotiating Acceleration

Acceleration provisions are most easily negotiated at the offer stage. Once your equity agreement is signed, adding acceleration is significantly harder. If you are joining a late-stage company where an acquisition is plausible, acceleration protection is worth requesting.

How Vesting Affects Your Exercise Strategy

Your vesting schedule directly shapes your exercise planning:

• Before the cliff: You cannot exercise (unless your plan allows early exercise of unvested options). No exercise decision is needed yet.
• At the cliff: A large tranche vests at once. This is often the first exercise decision point. If the spread is small, exercising early can lock in favorable tax treatment.
• During monthly vesting: You can exercise incrementally as options vest. Spreading exercises across calendar years can manage your tax bracket.
• Approaching departure: If you plan to leave, know exactly how many options will be vested on your last day and what the cost to exercise will be. Plan your post-termination exercise window before you give notice.

Understanding your vesting schedule is the first step in every exercise decision. Know the timeline, know the numbers, and plan accordingly.