Vesting is one of those concepts that sounds simple and becomes complicated in practice. At its core, the idea is straightforward: founders earn their equity over time rather than all at once. But the specific terms — how long the vesting schedule runs, what happens at a company sale, what investors can require when they write a check — have real consequences that are worth understanding before you sign anything.

Why Vesting Exists

Vesting protects the company and the remaining founders from a common early-stage disaster: a co-founder who leaves after a few months but takes a large block of equity with them. Without vesting, that person walks away with the same economic stake as someone who stayed for five years. With vesting, unvested shares return to the company when a founder departs — which means the remaining founders and future employees can be compensated from those shares rather than watching them sit idle with someone who is no longer contributing.

Institutional investors almost universally require that founder equity be subject to vesting before they invest. Even if outside investors are not yet in the picture, implementing vesting from the beginning is a sound practice. The conversation is much easier between co-founders at incorporation than it is after a term sheet arrives.

Standard Terms: What Market Looks Like

The market standard for founder vesting in a U.S. venture-backed startup is:

  • Four-year total vesting period.
  • One-year cliff. Nothing vests for the first twelve months. At the twelve-month anniversary, 25% of the total shares vest at once. This is the "cliff."
  • Monthly vesting thereafter. After the cliff, the remaining 75% vests in equal monthly installments over the following 36 months — approximately 2.08% of total shares per month.

This schedule is so common that deviating from it in either direction requires an explanation in most investor conversations. Shorter vesting schedules (three years, for example) are possible but unusual; longer schedules are almost never used for founders.

What "Vesting" Means for Restricted Stock

Most founders receive restricted stock — shares they purchase outright at incorporation at a low price, subject to a repurchase right held by the company. The repurchase right allows the company to buy back unvested shares at the original purchase price if the founder leaves before fully vesting.

When the repurchase right lapses — as shares "vest" — those shares become fully owned by the founder with no further risk of company repurchase. The founder paid $1,000 for 1,000,000 shares at grant; they own those shares outright as each tranche vests.

This is important for 83(b) election purposes as well: the taxable event for restricted stock is the vesting date under the default tax rule, which is why filing an 83(b) election immediately after receiving restricted shares is so important. (See our separate post on the 83(b) election for a full explanation.)

Acceleration: Single-Trigger vs. Double-Trigger

Acceleration provisions determine what happens to unvested shares when the company is acquired. There are two models:

Single-trigger acceleration means that a specified percentage of unvested shares vests automatically upon a change of control — the acquisition itself is the trigger, regardless of what happens to the founder's role afterward. A founder with single-trigger acceleration could receive 100% of their unvested shares at closing and then immediately leave the acquirer.

Double-trigger acceleration requires two events to trigger acceleration: (1) a change of control, and (2) a qualifying termination — the founder is terminated without cause or resigns for good reason within a specified window after the change of control (typically 12 to 18 months). If the founder is retained in a meaningful role post-acquisition and leaves voluntarily, unvested equity continues to vest under the original schedule.

Investors almost always resist single-trigger acceleration because it increases the cost of acquisition (the acquirer must compensate for shares that vest immediately without any retention obligation) and reduces the alignment between founder payout and post-closing contribution. If you request single-trigger acceleration in a seed financing, expect pushback.

Double-trigger acceleration is a reasonable and widely accepted protection for founders. It ensures that if an acquirer buys the company and immediately eliminates the founder's role, the unvested equity vests — rather than the founder losing it by being pushed out. This is a provision every founder should push for.

The typical double-trigger provision accelerates 50–100% of unvested shares upon a qualifying termination following a change of control. 100% acceleration is possible to negotiate; 50% is more easily accepted by investors.

Early Exercise Rights

Some companies allow founders who receive stock options rather than restricted stock to exercise their options before they vest — a feature called early exercise or early exercisability. If your company allows this, the mechanics work as follows:

  • You exercise the option at grant, paying the exercise price for all shares.
  • The shares are issued as restricted stock, subject to the same repurchase right the company would otherwise hold on unvested options.
  • Because you now hold actual shares (not just an option), you can file an 83(b) election within 30 days of the exercise date.
  • The tax benefit is the same as for founder restricted stock: you are taxed on the value of the shares at the time of exercise (when the FMV is likely close to the exercise price), not when they vest.

If your company allows early exercise, exercise on the day of the grant and file the 83(b) election the same week. This combination of early exercise and 83(b) election is one of the most effective tax planning steps available to startup employees and founders who receive options at early-stage companies.

What Investors Will Require at Series A

When institutional investors lead a priced round, they almost always require as a condition of investment that founders' unvested equity be subject to a vesting schedule going forward. If your company is 18 months old and you have already vested through the cliff, investors may acknowledge what you have vested and require that only the remaining unvested equity be subject to a going-forward schedule.

More aggressively, some investors push for a vesting "refresh" — putting some portion of previously vested equity back on a new vesting schedule tied to continued employment post-investment. This is most common when investors perceive that founders have vested through a significant portion of their schedule and want to ensure retention incentives remain strong.

Resist any restart that covers more than 50% of already-vested shares. The equity you have already earned represents the work you have done to build the company to the point where investors want to write a check. Giving back a substantial portion of vested equity as a condition of investment is a meaningful concession — one worth negotiating carefully.

The Practical Takeaway

Implement founder vesting at incorporation, even before you have outside investors. Use a four-year schedule with a one-year cliff. If your company grants options rather than restricted stock, consider whether early exercise is appropriate and document it correctly. Negotiate for double-trigger acceleration as a baseline protection. And when institutional investors arrive with their own vesting requirements, understand exactly what you are agreeing to before you sign.

The co-founder vesting conversation is awkward to have once there is a term sheet on the table. Have it at incorporation instead.