---
title: "Vesting Schedule, Cliff, Acceleration: The Complete Guide to Startup Equity Vesting"
description: "Vesting defines when you actually own your equity. Here's how 4-year schedules, 1-year cliffs, single/double-trigger acceleration, and early exercise work."
date: 2026-04-18T00:00:00.000Z
tags: ["vc-explainers", "equity-compensation", "startup-funding", "investor-education"]
source: https://venturecapitaltracker.com/what-is-a-vesting-schedule-4-year-cliff
---

# Vesting Schedule, Cliff, Acceleration: The Complete Guide to Startup Equity Vesting

> Vesting defines when you actually own your equity. Here's how 4-year schedules, 1-year cliffs, single/double-trigger acceleration, and early exercise work.

**Vesting** is the mechanism by which **equity you've been granted becomes yours over time**. Without vesting, a co-founder could quit after a month and walk away with half the company.

### The standard schedule

- **4 years total vesting**.
- **1-year cliff**: First 25% vests on the 1-year anniversary.
- **Monthly vesting** thereafter: 1/48 of total grant per month for months 13–48.

So on a 48,000-option grant:
- Month 1–11: 0 vested.
- Month 12 (cliff): 12,000 vested.
- Each subsequent month: 1,000 additional vested.
- Month 48: Fully vested.

### Variations

- **6-year vesting schedules** are used at some later-stage companies.
- **Back-weighted vesting** (e.g., 10/20/30/40) is rare but used when retention is high priority.
- **No cliff** for founders (if co-founders are long-term trusted partners).

### Why the cliff exists

Protects the company from an employee who doesn't work out but still walks with equity. Prevents "option mining" — joining for a short stint to bank options.

### Acceleration on acquisition

**Single-trigger acceleration**:
- All vesting accelerates upon a change-of-control event.
- Founder-friendly; acquirer-unfriendly.
- Rarely granted by VCs; more common for founders.

**Double-trigger acceleration**:
- Vesting accelerates **only if** the employee is terminated (or leaves for "good reason") within a defined window (commonly 12 months) after the acquisition.
- Market-standard for key employees.
- Protects employees from hostile acquirers while preserving incentives.

### Early exercise

Some companies allow **early exercise** of options — exercising before they vest. Benefits:
- Starts the long-term capital gains clock (U.S.).
- Potentially triggers 83(b) election for minimizing future tax.
- Requires upfront cash.

Risks:
- Forfeit cash if you leave before vesting completes (reverse-vesting mechanic).

### Founder vesting

Even founders typically agree to **4-year vesting with 1-year cliff** at the priced round. If a founder quits in year 2, unvested shares are clawed back into the pool.

Cooperative founders pre-agree on founder vesting before first outside money to avoid friction later.

### Refresh grants

Retention grants given periodically to top performers. Common patterns:
- **Year 3 refresh**: Extends effective equity horizon.
- **Promotion-based refresh**: New grant with a new vesting schedule.

### Common mistakes

1. **Founders skipping vesting** — creates massive conflict later.
2. **Not documenting acceleration terms** in offer letters — relying on plan default.
3. **Misunderstanding 83(b)** — 30-day filing deadline after exercise.
4. **PTEW trap**: Vesting continues during employment, but 90-day post-termination exercise window often forces cash exercise quickly after leaving.

### Practical takeaway

1. **Founders**: Negotiate double-trigger acceleration for yourself as part of priced rounds.
2. **Employees**: Ask about acceleration terms; they matter more than you think at exit.
3. **Investors**: Enforce clean, consistent vesting terms across the org.

### Further reading

- Carta Equity 101: https://carta.com/learn/equity/

**By:** [Venture Capital Tracker](https://venturecapitaltracker.com/editorial-policy)

**Editorial note:** AI tools assisted with research, structure, or drafting. Venture Capital Tracker retains human editorial responsibility for factual accuracy, relevance, and source quality before publication.