A Rancho Cucamonga dentist sells her practice to a dental group for $1 million plus up to $400,000 more if collections hold for two years, and stays on as an associate. Eighteen months later the group has moved a hygienist to Ontario and dropped Saturday hours, and the earnout statement says she missed by four percent. Delaware has spent years on a far bigger version; California has its own rules and a tax side.
What does a buyer owe a California seller while the earnout runs?
Less than most sellers assume. Carma Developers (Cal.), Inc. v. Marathon Development California, Inc., 2 Cal. 4th 342 (1992), requires good faith when one party holds “a discretionary power affecting the rights of another” (at 372), but “implied terms should never be read to vary express terms” (at 374). If the agreement gives the buyer sole discretion over staffing or hours, using it usually is not a breach. I see that clause in most buyer-side first drafts.
The rule is sharper when the buyer makes payment impossible. In Pacific Venture Corp. v. Huey, 15 Cal. 2d 711, 717 (1940), buyers owing a $2,500 balance payable from mining royalties transferred the claims and still owed it, because “a person cannot avoid liability for the nonperformance of an obligation by placing such performance beyond his control.” Cal. Civ. Code § 1511 and § 1512 state a cousin of that rule. Delaware just tested how far that idea reaches.
What did the Delaware court decide in the Alexion earnout case?
Alexion bought Syntimmune in 2018 with up to $800 million in milestone payments and efforts measured against “biopharmaceutical companies similar in size and scope.” The September 5, 2024 liability opinion treated that as an objective test measured by a hypothetical comparable and held that killing the program, a decision “driven by AstraZeneca’s pursuit of merger synergies” after AstraZeneca bought Alexion, breached it. A sole-discretion clause did not help; it “was cabined by” the efforts promise.
The June 11, 2025 damages opinion awarded $180,944,915.32 plus interest, weighting each unpaid milestone by its probability (from Alexion’s own pre-breach estimates) and discounting to present value. The sellers sought every payment, about $755 million with interest, under the prevention doctrine, which the court held “does not provide a plaintiff a back door to damages in excess of proven expectation damages.”
Alexion later won about $12 million on an indemnification claim, and an August 3, 2026 letter cleared the way for final judgment. I find no Delaware Supreme Court decision as of mid-October 2026; any appeal would follow that judgment. Mid-2025 commentary predates all of this.
How would a California court value a lost earnout, and whose law applies?
Cal. Civ. Code § 3300 compensates “all the detriment proximately caused,” and § 3301 bars damages “not clearly ascertainable in both their nature and origin.” Sargon Enterprises, Inc. v. University of Southern California, 55 Cal. 4th 747 (2012), upheld excluding an expert’s market-share projections for a small dental implant company; lost profits “must also not be unduly speculative.” So the seller’s proof is the business’s own record. I expect California would land near Delaware’s answer, though I have found no published California earnout case on point.
Many deals pick Delaware law. Nedlloyd Lines B.V. v. Superior Court, 3 Cal. 4th 459, 466 (1992), enforces the choice if there is a substantial relationship or other reasonable basis, unless it offends a fundamental California policy and California has a materially greater interest. The implied covenant is no such policy. 6 Del. C. § 2708 presumes a Delaware choice reasonable in contracts of $100,000 or more. A Riverside seller who signs it should treat Alexion as the rulebook.
What should a seller insist on before signing an earnout?
First, define the effort. Alexion’s peer-company test took a trial to give it meaning. In a small deal I tie effort to the buyer’s conduct at similar locations, or to checkable numbers such as minimum office hours and a marketing budget. Then strike or narrow sole-discretion language, which under Carma can defeat the implied covenant.
Measure gross revenue or collections, not EBITDA, which moves whenever the buyer charges management fees or overhead to the location. The business should stay a separate reporting unit with unchanged accounting methods, and monthly reports plus an audit right let the seller’s accountant test the statement while objections still matter.
I also want acceleration if the buyer sells the business or fires the seller without cause; Alexion’s program died after its own buyer arrived. Calculation fights belong with an independent accountant on a short clock, effort fights in court. Follow notice clauses exactly, too; the Alexion sellers’ fee claim stalled for lack of a shown indemnification notice.
How are earnout payments taxed for a California seller?
Usually as installment sale proceeds. A sale whose price cannot be fixed by year-end is a contingent payment sale under IRC § 453 and Treas. Reg. § 15a.453-1(c). With a cap, basis is allocated as if every contingency is met; with only a fixed term, evenly over the term; with neither, over 15 years. Equipment recapture is taxed in the year of sale under § 453(i). Under IRC § 483 and Treas. Reg. § 1.483-4 (or § 1.1275-4(c) if § 1274 applies), each contingent payment is discounted to the sale date at the applicable federal rate, and the excess is ordinary interest.
If the earnout vanishes when the seller stops working there, the IRS can call it wages, and buyers may not object, since wages are deducted at once and goodwill over 15 years under IRC § 197. California adopts the installment rules through Cal. Rev. & Tax. Code § 17551 but taxes capital gain in the same 9.3 to 12.3 percent brackets as wages, plus 1 percent over $1 million (§ 17043). So the label barely moves California income tax; the swing is federal, plus payroll tax, including State Disability Insurance at 1.3 percent of all 2026 wages. For any real estate in the deal, § 18662(e) generally requires 3 1/3 percent withholding.
Illustrative numbers for the opening dentist, Dr. Ortiz: she closes in November 2026 for $1,000,000 plus $200,000 for each of 2027 and 2028 if collections reach $1.1 million. Say $100,000 of the closing cash goes to fully depreciated equipment and the rest to zero-basis goodwill. Her 2026 return shows $100,000 of ordinary recapture and $900,000 of capital gain. At an assumed 4 percent federal rate, the 2027 payment is about $192,300 of gain and $7,700 of interest; the 2028 payment, about $184,900 and $15,100.
As price, the $400,000 costs roughly $65,000 to $84,000 of federal income tax at 15 or 20 percent. As wages, about $140,000 to $148,000 at 35 to 37 percent, plus roughly $9,400 of Medicare tax and $5,200 of SDI at the 2026 rate, assuming her salary already tops the additional Medicare threshold and the Social Security wage base ($192,300 for 2027). California income tax, around $37,000 to $49,000, does not change. The label is worth roughly $80,000 to $90,000, so I tie the earnout to practice numbers, not to her staying.
What closing steps keep old tax debts from eating the earnout?
An unpaid earnout is the easiest money to hold back. Cal. Rev. & Tax. Code § 6811 requires a buyer to withhold enough of the price for the seller’s sales and use tax until CDTFA issues a receipt or certificate, and under § 6812 a buyer who skips it is liable up to the price. Cal. Unemp. Ins. Code §§ 1731 and 1732 work the same way for EDD. Inventory sellers and restaurants (most franchise food units and e-commerce brands) also face the bulk sale rules (Cal. Com. Code § 6103): notice 12 business days before closing under § 6105 and, at $2 million or less, payment of timely claims from the cash under § 6106.2. A dental practice usually falls outside them. Clear all of it before closing so the earnout is not later offset. (See my post on what a section 363 sale order does not cut off.)
| Design choice | Seller risk | Buyer risk | What the Delaware case shows |
|---|---|---|---|
| Effort: undefined vs. defined | Undefined: implied covenant only | Defined: duties it can breach | An objective definition beat sole discretion |
| Metric: EBITDA vs. revenue vs. units | EBITDA: allocations erase payment | Revenue: pays on thin margins | Each milestone’s probability set damages |
| Control: none vs. separate reporting unit | None: folded into the parent | Separate unit: slower integration | A new parent’s synergy push ended the program |
| Acceleration: none vs. on sale or termination | None: earnout dies in a later deal | Pays before targets are met | Without it, expected value, not face amount |
| Disputes: litigation vs. accountant | Litigation: years and fees | Accountant: fast, narrow review | Filed in 2020, no final judgment by August 2026 |
Frequently Asked Questions
Is an earnout taxed at closing or when it is paid in California?
Usually when it is paid. California follows the federal installment rules, so gain on each payment is reported in the year it arrives, with part of it treated as interest.
Can a buyer close the business and owe nothing on the earnout?
Not if the contract has an effort clause, and California law also stops a party from escaping a payment by making its condition impossible. Expect the fight to be over the amount, usually the earnout’s realistic value rather than its face amount.
Does California give a lower tax rate on earnout gain?
No. California taxes capital gain at the same rates as wages, generally 9.3 to 12.3 percent at these income levels, plus 1 percent above $1 million, so the real difference is federal.
Should a California seller agree to Delaware law in the purchase agreement?
Usually California courts enforce the choice, and Delaware presumes it reasonable for contracts of $100,000 or more. A seller who accepts it should expect Delaware’s earnout cases to decide the dispute.
What happens to my earnout if the buyer sells the business?
Without an acceleration clause, it rides along and depends on how the next owner runs things. With one, the unpaid amount comes due at an agreed figure on a sale or a termination without cause.
How North Star Law Firm Can Help
North Star Law Firm represents California sellers and buyers in buying and selling a business, negotiates earnout terms through contract drafting and review, and models the tax through business sale tax structuring. Phillip Zagotti is a California attorney and a CPA, admitted to the U.S. Tax Court.
If a buyer has sent you an earnout term sheet, contact North Star Law Firm or schedule a consultation before the effort clause is final.








