Single-Trigger and Double-Trigger Acceleration in Founder Agreements
Acceleration provisions determine how fast unvested founder equity vests at acquisition. Single-trigger, double-trigger, and modified variants each shift risk between founder and acquirer.
A founder with 6 million shares of reverse-vesting stock gets an acquisition offer: $80 million total, $5 per share. She has 4 million shares vested (two years in) and 2 million shares still subject to vesting over the next two years. Under her restricted stock purchase agreement, her unvested shares don’t automatically vest at closing. The acquirer requires her to stay for two more years to unlock the remaining shares.
If she quits, she forfeits 2 million shares at $5 each: $10 million of potential proceeds walks away. If she stays, she is at the mercy of the acquirer (who could fire her without cause or force a difficult role change). Her acceleration provision, buried in the RSPA as “double-trigger” language, says: if she is terminated without cause or resigns for good reason within 18 months of closing, her remaining unvested shares accelerate.
This is double-trigger acceleration. It protects her against the acquirer firing her to avoid vesting, while preserving the acquirer’s ability to retain her if they want to.
Understanding acceleration structures is essential for founders negotiating RSPAs and for any founder facing an acquisition event.
The three primary structures
Single-trigger acceleration. All or a portion of unvested shares accelerate at change of control, regardless of employment status. Upon the acquisition closing, vesting happens.
Double-trigger acceleration. Two conditions must occur: (1) change of control AND (2) termination without cause or resignation for good reason within a specified window (typically 12-24 months post-closing).
Modified single-trigger or partial acceleration. Hybrid: partial single-trigger plus full double-trigger. E.g., 50% vests at closing (single-trigger), remainder upon involuntary termination within the post-closing window.
What investors prefer
Series A and later investors strongly prefer double-trigger or no acceleration. Their reasoning:
- Acquirers pay less for companies where key personnel can walk away immediately at closing with fully vested equity.
- Single-trigger creates a “takes the money and runs” incentive for founders.
- Double-trigger preserves the founder’s incentive to stay while protecting against bad-actor acquirers.
Investor pushback on single-trigger is one of the most common term sheet negotiations. Founders often accept double-trigger in exchange for other concessions.
What founders prefer
Founders want single-trigger (or full single-trigger) because:
- It removes the risk of being fired by the acquirer without cause.
- It maximizes the founder’s leverage in deciding whether to join the new company.
- It reflects the founder’s effort invested before the acquisition.
Founders also want the double-trigger window to be long (18-24 months) rather than short (6-12 months), and the “good reason” definition to be broad (significant role change, pay reduction, relocation, reduction in responsibilities).
The negotiated outcomes
Typical founder acceleration outcomes after investor negotiations:
| Stage | Typical acceleration |
|---|---|
| Seed-stage founder | Full single-trigger (not yet negotiated down) |
| Post-Series A | Full double-trigger |
| Senior executive joining Series B+ | Full or partial double-trigger |
| Early engineer at Series C+ | Partial double-trigger or limited |
| Independent director | Usually no acceleration |
Founder acceleration at Series A is often where companies lose single-trigger rights they had at seed stage. The Series A lead can insist on double-trigger for all founder stock as a closing condition.
The “good reason” definition
For double-trigger to protect the founder, “good reason” must be defined broadly enough to prevent the acquirer from simply demoting the founder into an unpleasant role rather than firing them.
Typical “good reason” elements:
- Material reduction in base salary or bonus opportunity.
- Material diminution in position, authority, duties, responsibilities, or reporting lines.
- Relocation requirement beyond a specified distance (typically 30-50 miles).
- Material breach of the employment agreement by the employer.
Defining these well is essential. An acquirer can sometimes accomplish “constructive termination” without technically firing the founder; tight “good reason” language prevents this.
Notice and cure provisions are standard: the founder must notify the acquirer of the “good reason” circumstance and give them 30-60 days to cure. If not cured, the founder can then resign for good reason and claim acceleration.
The IRS treatment
Acceleration events create taxable income. For founders with timely 83(b) elections on restricted stock:
- Shares were already fully recognized at grant.
- Acceleration of vesting does not trigger additional ordinary income.
- Upon sale (at or after acquisition), gain is capital gain.
For founders without 83(b) on restricted stock:
- Each acceleration triggers ordinary income on the spread between FMV at acceleration and purchase price.
- At acquisition, the entire remaining unvested block vests and creates a large ordinary-income event on the acquisition date.
For founders with stock options (not 83(b)-eligible property):
- Acceleration of vesting allows exercise of previously unvested options.
- Exercise creates ordinary income on the spread at exercise (for NSOs) or AMT exposure (for ISOs).
- Large acquisition-related acceleration can produce very large immediate income events.
Section 280G and the “golden parachute” issue
IRC §280G applies to “excess parachute payments” to disqualified individuals (certain executives and officers). A payment is a parachute payment if contingent on change of control and exceeds three times the individual’s “base amount” (5-year average compensation). Excess parachute payments lose a deduction for the company (and the founder owes a 20% excise tax under §4999).
Acceleration payments can be parachute payments. For founders whose acceleration would cause 280G exposure:
- Pre-closing, compute “base amount” and the 3× threshold.
- Compare the acceleration value to the threshold.
- If above threshold, consider §280G planning: “cutback” (reduce the acceleration to stay below), gross-up (company pays the excise tax, though this is less common), or shareholder approval under §280G(b)(5) safe harbor.
The shareholder approval safe harbor requires that 75%+ of shareholders approve the parachute payments after disclosure, before the transaction closes. For private companies with concentrated ownership this is usually achievable.
Interaction with equity-comp tax withholding
At acceleration, the company must withhold on the income. For restricted stock without 83(b):
- Withholding at supplemental rates (22% federal, or 37% if over $1M annual supplemental wages).
- State withholding per state rules.
- Company often allows “sell to cover” or “net settlement” to pay the withholding from the shares themselves.
For large acceleration events, the tax withholding is substantial and needs pre-planning.
Comparison: acceleration structures compared
| Structure | Founder benefit | Acquirer pays | Investor acceptance |
|---|---|---|---|
| Full single-trigger | Maximum | Maximum | Low, resisted |
| 50% single-trigger + double-trigger on rest | Strong | Moderate | Sometimes accepted |
| Full double-trigger | Protects against termination | Lower | Standard |
| Partial double-trigger (e.g., 50% at termination) | Moderate | Moderate | Sometimes |
| No acceleration | None specific to CoC | Lowest | Acceptable to investors |
Founders’ typical negotiating posture
In seed/Series A negotiations, founders who understand the structures push for:
- Single-trigger on at least a portion (25-50%) of unvested stock.
- Double-trigger on the remainder with 18+ month window.
- Broad “good reason” definition.
- Continued vesting credit for time since grant even if single-trigger not accepted.
Founders who don’t push often end up with full double-trigger, which is the investor default and not a bad outcome but is less favorable than partial single-trigger.
Frequently asked
Can I get acceleration added after signing the RSPA? Amendments to the RSPA require board approval and often investor consent. Generally difficult to add acceleration retroactively after a financing.
Does acceleration apply if I quit to join a competitor? Only if your RSPA and acceleration provisions cover voluntary departures. Typically voluntary departures do not trigger acceleration; only involuntary terminations or “good reason” resignations.
What about acceleration upon the founder’s death? Many RSPAs include death-acceleration, fully vesting the shares to the estate. This is separate from change-of-control acceleration.
How is acceleration valued for 280G? §280G has specific rules for valuing accelerated vesting. The value is determined by the incremental vesting caused by the CoC and the specific methodology under the regulations.
Can acceleration cause QSBS holding period issues? Acceleration of vesting does not affect the QSBS holding period for shares that were already owned (with 83(b) filed). The shares were “owned” from the original grant.
Next step
If you are a founder negotiating an RSPA at any financing stage, review the acceleration provisions carefully with counsel before signing. The specific language on single-trigger percentage, double-trigger window length, and “good reason” definitions can materially affect outcomes years later. For founders facing an acquisition, review acceleration provisions before the LOI is signed; negotiation leverage shifts quickly once a deal is in motion.
Economist advising founders on equity structure from formation through exit. Reviews VestedGrant's founder equity content.
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