What is a success fee in M&A?
A success fee is compensation due at closing, calculated as a percentage of the consideration the seller receives. No closing means no success fee, which is why the fee is paired with a monthly retainer that funds the work in the meantime.
Market rates scale down as deals grow: 4 to 6 percent below $10 million of enterprise value, 2 to 4 percent between $10 million and $50 million, and 1 to 2 percent above $100 million, with boutique minimum fees of $400,000 to $750,000. Full market data sits on the Windsor Drake M&A advisor fees page, and what an M&A advisor costs covers the total bill including retainers and expenses.
What counts as consideration?
Consideration is every form of value the seller receives, and the definition in the engagement letter decides what the fee is charged on. Cash at close is always in. Earnouts, rollover equity, escrows, holdbacks, and assumed debt are in or out depending on drafting, and the difference is worth six figures on a mid-market deal.
The seller-favorable positions are specific. The fee on an earnout is paid when and if the earnout is earned, and the fee on an escrow is paid when the escrow releases. Rollover equity is valued at the deal price rather than at a projected future value. An advisor who resists those positions is telling you where the incentives sit.
What does a success fee make your advisor want?
A pure percentage fee aligns the advisor on price, and it aligns the advisor even harder on closing at all. On a $25 million deal at 3 percent, one extra million of price is worth $30,000 to the advisor, while the difference between closing and not closing is worth $750,000. Roughly 1 in 3 signed LOIs fail to close on original terms, so the pressure to get any deal done is real and a flat fee feeds it.
Minimum fees exist to keep small deals staffed, because below $10 million of enterprise value a bare percentage would not fund a senior team for a 6 to 10 month process. Tiered fees above a threshold are the seller-favorable design, because the ratchet pays the advisor most on the last dollar, which is the dollar that was actually in dispute.
Which fee designs serve the seller?
Tiered structures with a ratchet above a threshold serve the seller most, and declining Lehman-style scales serve the seller least. The table below reads each common design for what it pays the advisor to do.
| Fee design | Advisor incentive | When it serves the seller |
|---|---|---|
| Flat percentage | Close the deal; every million adds the same marginal fee | Clean deals with a wide buyer field and no contested price gap |
| Minimum fee | Keep senior staff on the mandate even when the deal is small | Deals below roughly $10 million EV where a bare percentage would not fund the work |
| Tiered ratchet above a threshold | Push price past the threshold; the last dollar pays the most | Sellers with a clear walk-away number who want the advisor paid to beat it |
| Declining scale (Lehman-style) | Get to any close; the contested increment pays the least | Rarely, since the design pays most on the millions that were never in doubt |
The declining-scale design has its own page at the Lehman formula, explained and priced.
What should you negotiate in the engagement letter?
Negotiate the consideration definition first, because the definition moves more money than the headline rate. Pin down the treatment of earnouts, escrows, rollover, and assumed debt in writing before signing.
Negotiate four more terms: a tail bounded at 12 to 18 months with a named buyer list, a tiered structure that ratchets above your walk-away number, retainer payments credited against the success fee, and termination rights on 30 days notice. Advisors who run real processes accept all four, since each term only bites when the advisor underperforms.
What is a tail clause, and is it reasonable?
A tail clause entitles the advisor to the success fee if the seller closes with a buyer the advisor introduced within a set window after termination, commonly 12 to 24 months. The clause is standard and reasonable, because without it a seller could absorb six months of outreach, fire the advisor, and close fee-free with a buyer the advisor produced.
Bound the tail rather than fighting it. Limit the window to 12 to 18 months and limit coverage to a named schedule of buyers the advisor actually contacted. Buyers who approached the company before the engagement began belong outside the tail.
How do flat and tiered fees compare on a $25 million deal?
A flat 3 percent fee on a $25 million closing pays the advisor $750,000. A tiered structure of 2 percent plus 6 percent on everything above $22 million pays $500,000 plus $180,000, a total of $680,000 on the same deal.
The totals hide the incentive difference. Under the flat fee, the 25th million is worth $30,000 to the advisor; under the tier, the same million is worth $60,000. The tiered advisor is paid double to fight for the increment the buyer is resisting, and above $26.4 million the tiered fee overtakes the flat fee entirely.
The fee debate is second order next to The Proprietary Discount, the gap between what a serial acquirer pays in an unbanked bilateral negotiation and what the same business clears in a competitive process. Windsor Drake pegs that gap at 15 to 25 percent of enterprise value, which on a $25 million deal is $3.75 million to $6.25 million, against a fee measured in hundreds of thousands. Windsor Drake’s sell-side process shows the work the fee actually buys.
What are the red flags in an M&A fee agreement?
A fee charged on gross transaction value with no consideration definition is the first red flag, because it invites a fee on debt the buyer assumes and on earnouts that never pay. Uncapped expense reimbursement is the second red flag, and the fix is a monthly cap with receipts.
A perpetual tail, or a tail covering any buyer regardless of introduction, is the most expensive red flag. A seller who signs an unbounded tail owes a fee on a deal the advisor had nothing to do with, years after the engagement ended. The offer-received hub covers how these terms interact with a live approach.
If you are holding a live inbound offer and want the engagement terms priced before you sign anything, Approach Response is the Windsor Drake engagement for that position.
Questions founders ask
What percentage do M&A advisors charge at closing?
Success fees run 4 to 6 percent below $10 million of enterprise value, 2 to 4 percent between $10 million and $50 million, and 1 to 2 percent above $100 million. Boutique minimum fees run $400,000 to $750,000.
Is the retainer credited against the success fee?
Retainer credit is common and negotiable. Many boutique advisors credit some or all retainer payments against the success fee at closing, and the engagement letter should state the credit explicitly rather than leaving it implied.
Do I owe a success fee on an earnout?
Under a seller-favorable engagement letter, the fee on an earnout is due when and if the earnout is actually paid, not at closing on the earnout’s face value. The consideration definition controls the outcome, so negotiate it before signing.
What is a tail period in an M&A engagement letter?
A tail period entitles the advisor to the success fee if the seller closes with an introduced buyer within a set window after termination, commonly 12 to 24 months. Bound the tail to 12 to 18 months and to a named schedule of buyers the advisor actually contacted.
What happens to the fee if the deal falls through?
No closing means no success fee, and the advisor keeps retainer payments already made. Roughly 1 in 3 signed LOIs fail to close on original terms, which is the risk the retainer-plus-success-fee model splits between seller and advisor.
Are M&A success fees negotiable?
Structure is more negotiable than the headline rate. Sellers get more value from a tight consideration definition, a bounded tail, and a ratchet above the walk-away number than from shaving half a point off the base percentage.
Last reviewed July 28, 2026 by Jeff Barrington, Founder and Managing Director, Windsor Drake. Content on this page may be cited with attribution and a link to https://windsordrake.com/services/how-success-fees-work/