A success fee is a performance-based payment that comes due only when a specific transaction closes or a defined outcome is achieved. It is most common in investment banking, business brokerage, and the legal profession, where it goes by the name contingency fee. Rates run from under 1% on billion-dollar mergers to 10% or more on small business sales, and the structure lines up the advisor’s payday with the client’s goal. The details buried in the engagement letter, though, often decide whether the arrangement is a good deal or an expensive one.
How the Payment Is Structured
Most success fee arrangements pair a modest upfront payment with a larger back-end payout. The upfront piece is usually a fixed engagement fee or a monthly retainer that covers the advisor’s overhead while the work is underway. The success fee itself fires only when the deal closes, calculated as either a flat dollar amount or a percentage of the transaction value. The two-part structure lets the advisor commit real resources without bearing the full risk of a deal that never happens.
Many agreements add a performance hurdle. A hurdle means the success fee only kicks in if the final price clears a specified floor. An advisor might earn nothing extra unless the acquisition price passes $50 million, for example. Hurdles protect the seller from paying a premium for a mediocre result and push the advisor to maximize value rather than just close any deal.
Tail provisions are the clause most clients overlook and most advisors insist on. A tail guarantees that if a transaction closes with a buyer the advisor originally introduced, the advisor still earns the fee even after the engagement has formally ended. Tail periods in investment banking typically run 12 to 24 months after termination. Without a tail, a client could fire an advisor the week before closing and avoid the fee entirely, which is why advisors treat this term as non-negotiable.
Typical Rates by Deal Size
Success fee percentages move inversely with deal size. The smaller the transaction, the higher the rate needs to be for the advisor’s work to pencil out. The larger the deal, the lower the percentage, because even a fraction of a percent translates to millions of dollars.
- Under $2 million: fees generally range from 8% to 12%. The advisor is doing nearly the same amount of work as on a larger deal, so the percentage compensates for the smaller dollar payout.
- $2 million to $10 million: rates typically fall between 5% and 8%. The pool of qualified buyers tends to be larger, which can shorten the time to close.
- $10 million to $100 million: mid-market transactions usually carry fees in the 2% to 6% range, with the percentage declining as you move up the bracket.
- Over $100 million: fees drop to roughly 1% to 2%, and on transactions above $500 million, they regularly fall below 1%. A 0.5% fee on a $2 billion merger still produces $10 million in compensation.
These ranges are market conventions, not fixed rules. Every engagement is negotiable. The difficulty of the assignment, the advisor’s track record in the industry, and whether the deal involves a competitive auction or a single targeted buyer all shift the rate.
The Lehman Formula
The Lehman Formula is a tiered calculation model that has been used in investment banking for decades. It applies decreasing percentages to successive tranches of the transaction value:
- 5% on the first $1 million
- 4% on the second $1 million
- 3% on the third $1 million
- 2% on the fourth $1 million
- 1% on everything above $4 million
On a $6 million deal, the fee would be $50,000 + $40,000 + $30,000 + $20,000 + $20,000 = $160,000, or about 2.7% of the total. The tiered structure means the effective rate declines as deal size grows.
For smaller transactions, particularly those under $5 million, many brokers use the Double Lehman formula, which doubles each tier: 10% on the first million, 8% on the second, 6% on the third, 4% on the fourth, and 2% above $4 million. A small-business sale can take six to twelve months to close, and the original Lehman percentages do not generate enough fee income to justify that commitment on a deal worth $2 or $3 million.
Equity Value vs. Enterprise Value
The single most important detail in any Lehman-based engagement letter is how “transaction value” is defined. The formula can be applied to equity value (what the buyer actually pays the seller) or enterprise value (equity plus the company’s assumed debt). On a company with $10 million in equity value and $5 million in debt, enterprise value is $15 million, and the fee difference between the two bases is substantial. Clients naturally prefer the equity basis; advisors prefer enterprise value. Pin this down in writing before any work begins.
Contingency Fees in Legal Work
In the legal profession, success fees are called contingency fees and serve a different purpose: they let people who cannot afford hourly rates pursue claims they would otherwise have to abandon. The lawyer advances the cost of litigation and collects a percentage of the recovery only if the case succeeds. If there is no recovery, the client typically owes no legal fee.
The standard range for personal injury contingency fees is roughly 33% if the case settles before a lawsuit is filed and 40% once litigation begins. Cases that go through a full trial or appeal can push the fee to 45% or higher, depending on the jurisdiction and the agreement. Those percentages reflect that a case requiring years of discovery, depositions, and trial preparation costs the lawyer far more than one that resolves with an early demand.
ABA Model Rule 1.5 sets the professional guardrails. The rule requires that every contingency fee agreement be in writing, signed by the client, and spell out the percentage the lawyer will receive at each stage, how expenses will be handled, and whether those expenses come off the top before or after the fee is calculated.1American Bar Association. Model Rules of Professional Conduct – Rule 1.5 – Fees When the matter concludes, the lawyer must provide a written statement showing the outcome, the recovery amount, and how the fee was calculated.
The same rule flatly prohibits contingency fees in two categories: criminal defense and domestic relations matters where the fee depends on securing a divorce or is tied to the amount of alimony, support, or property division.1American Bar Association. Model Rules of Professional Conduct – Rule 1.5 – Fees Violating these rules can result in forfeiture of the fee and disciplinary action.
Terms That Change the Total Cost
The headline percentage is only one piece of a success fee arrangement, and often not the most expensive one. Several other terms in the engagement letter shift the total significantly.
- Minimum fees. Many advisors set a floor dollar amount regardless of what the percentage formula produces. If the deal closes at a lower price than expected, the minimum can push the effective rate well above the stated percentage.
- Fee caps. Caps work in the opposite direction, capping the total fee even if the percentage would produce a higher number. These are more common in larger transactions where the advisor’s effort does not scale linearly with deal value.
- Calculation base. Whether the fee applies to equity value or enterprise value can change the total by tens or hundreds of thousands of dollars.
- Tail length. A 24-month tail is standard in investment banking, but shorter periods are negotiable, especially after a brief engagement. Some agreements narrow the tail to cover only specific buyers the advisor identified.
- Expense reimbursement. Even in a pure success fee arrangement, most engagement letters require the client to reimburse out-of-pocket expenses like travel, data room costs, and third-party research regardless of whether the deal closes. Check what is covered and whether there is a cap.
The time to negotiate all of this is before signing. Once an advisor has invested months of work and introduced your company to buyers, leverage to renegotiate evaporates.
When Paying a Success Fee Triggers Broker Registration
Paying a success fee to someone who helped arrange the sale of a business can create a securities problem. Under the Securities Exchange Act, anyone who effects securities transactions for compensation generally must register as a broker-dealer with the SEC, and accepting a transaction-based fee has long been treated as one of the hallmarks of broker-dealer activity.
The stakes are high. Contracts made in violation of the Act’s registration requirements can be voided, meaning the underlying transaction itself may be unwound.2Office of the Law Revision Counsel. 15 US Code 78cc – Validity of Contracts Investors may have the right to rescind the deal and demand their money back, potentially with interest and attorneys’ fees. The collector of the fee can face SEC enforcement, and the taint on the transaction can derail future financing rounds when it surfaces during due diligence.
Federal law does carve out an exemption for “M&A brokers” who facilitate the sale of eligible privately held companies. Under 15 U.S.C. ยง 78o(b)(13), an M&A broker can collect success fees without registering, provided the broker stays within defined guardrails.3Office of the Law Revision Counsel. 15 USC 78o – Registration and Regulation of Brokers and Dealers The target must be privately held with either EBITDA under $25 million or gross revenues under $250 million in the most recent fiscal year. The exemption disappears if the broker handles funds or securities, provides financing, represents both sides without written consent, or facilitates a sale to passive buyers. Before paying a success fee to an unregistered intermediary, confirm the exemption actually applies.