In a contingent payment sale, the IRS treats each deferred payment as two things at once: a slice of imputed interest taxed to the seller as ordinary income and deductible by the buyer, and a principal slice the seller usually reports as capital gain under the installment method while the buyer adds it to the basis of the acquired assets. The tricky part is that the total selling price often isn’t known at closing, so the tax code and Treasury Regulations lay out specific mechanics for spreading basis and recognizing gain when payments hinge on future events.
How Each Payment Gets Split Between Interest and Principal
Whatever the contract says about interest, the IRS carves an interest piece out of every contingent payment that’s due more than a year after the sale. Under IRC Section 483, if the contract either charges no interest or charges interest below the applicable federal rate, part of each payment is recharacterized as “unstated interest.”1Office of the Law Revision Counsel. 26 US Code 483 – Interest on Certain Deferred Payments
The applicable federal rate is published monthly by Treasury and comes in three flavors tied to the payment term: short-term (three years or less), mid-term (three to nine years), and long-term (over nine years). Sellers can use the lowest rate from the three-month period ending with the month of the sale.2Office of the Law Revision Counsel. 26 US Code 1274 – Determination of Issue Price in the Case of Certain Debt Instruments Issued for Property For contingent payments specifically, the interest allocation follows a method consistent with the original issue discount rules.3eCFR. 26 CFR 1.483-4 – Contingent Payments
The character difference matters. Imputed interest is ordinary income to the seller, which in most brackets is taxed well above the long-term capital gains rate. The principal portion is what gets the more favorable treatment.
A few sales sit outside Section 483. It doesn’t apply to sales with a total price of $3,000 or less, to certain patent transfers where the payment depends on the patent’s productivity, or to transactions that instead fall under the original issue discount rules of Section 1274.4Office of the Law Revision Counsel. 26 USC 483 – Interest on Certain Deferred Payments
Reporting Gain When the Total Price Isn’t Fixed
After the interest slice is peeled off, the principal is generally reported under the installment method, letting the seller recognize gain as cash arrives instead of all in the year of sale.5Office of the Law Revision Counsel. 26 USC 453 – Installment Method The obstacle for contingent sales is that the standard installment calculation needs a total selling price, and a contingent deal by definition doesn’t have one at closing.
The Treasury Regulations solve this with three scenarios, each with its own way of recovering the seller’s basis:6eCFR. 26 CFR 15a.453-1 – Installment Method Reporting for Sales of Real Property and Casual Sales of Personal Property
- Maximum selling price is determinable. If the contract lets you calculate the highest possible total (assuming every contingency breaks in the seller’s favor), that ceiling is treated as the selling price. Basis is allocated across payments using that number, and if actual payments come in lower, the seller adjusts in the year the shortfall becomes clear.
- No maximum price, but a fixed payment period. When there’s no cap on total payments but the contract limits them to a set number of years, basis is spread equally across those years. The seller recovers the same amount of basis each year regardless of the size of the actual payment.
- No maximum price and no fixed period. The IRS looks at these skeptically and will question whether a true sale occurred. If it qualifies, basis is recovered in equal installments over 15 years from the sale date.
The installment method isn’t available across the board. Sales of inventory, publicly traded securities, and dealer dispositions are excluded. Sales of depreciable property to a related party get special treatment where all payments may be deemed received in the year of sale.5Office of the Law Revision Counsel. 26 USC 453 – Installment Method A seller can also elect out and recognize all gain in the year of sale.
The Open Transaction Exception
In rare cases where the fair market value of the contingent payment obligation genuinely cannot be determined, the seller can use open transaction treatment. The seller recovers their entire basis first, and only payments after that point produce gain. The IRS treats this as an extraordinary result, and the regulations make clear that most contingent obligations do have an ascertainable fair market value.6eCFR. 26 CFR 15a.453-1 – Installment Method Reporting for Sales of Real Property and Casual Sales of Personal Property
The Buyer’s Side
The buyer’s tax position mirrors the seller’s. Contingent payments to the seller are additional purchase price, not deductible business expenses. Each payment (net of the interest portion) is added to the buyer’s tax basis in the acquired assets or stock.
The imputed interest portion is generally deductible by the buyer as interest expense, offsetting the ordinary interest income the seller must report on the same amount. Timing follows when the payment obligation becomes fixed and determinable, which is typically the moment the contingency is met.
Amortizing New Goodwill When a Later Payment Hits
In an asset acquisition, additional purchase price from a contingent payment gets allocated across the acquired assets using the residual method the IRS requires. Fair market value is assigned first to tangible assets and identifiable intangibles, and any remainder goes to goodwill. Goodwill and most other acquired intangibles (customer lists, patents, workforce in place, covenants not to compete, trade names) are amortized ratably over 15 years.7Office of the Law Revision Counsel. 26 USC 197 – Amortization of Goodwill and Certain Other Intangibles
When an earn-out payment is later triggered and total purchase price rises, the buyer must re-allocate the additional amount and start amortizing any new goodwill from the month the additional amount is determined. That 15-year clock for the incremental goodwill starts fresh at settlement, not at the original acquisition date.
When the Payment Gets Reclassified as Compensation
Everything above assumes the contingent payment is purchase price. If the IRS or an auditor decides it’s really compensation for the seller’s post-acquisition services, the treatment flips. The payment becomes a deductible expense for the buyer, spread over the service period, and the seller reports it as ordinary wage income instead of capital gain.
FASB identifies several indicators that separate purchase consideration from compensation. The strongest is an employment tie: if the earn-out is automatically forfeited when the seller leaves the company, it looks like compensation. If the payments continue regardless of employment status, it looks like purchase price. Other indicators include whether the required employment period matches the earn-out period, whether the seller’s base salary is reasonable compared to peers (an unusually low salary suggests the earn-out is filling that gap), and whether sellers who don’t become employees receive different per-share earn-out amounts than those who do.
How the earn-out formula was built also matters. If the upfront price sat at the low end of the valuation range and the earn-out was designed to bridge to the high end, that supports purchase-price treatment. If the formula has no relationship to the valuation, it looks more like a bonus.
The Section 409A Penalty
When an earn-out is tied to continued employment, it can be treated as deferred compensation under Section 409A. Non-compliant deferred compensation triggers immediate tax on the full deferred amount once there’s no substantial risk of forfeiture, plus a 20% additional tax on that amount and a premium interest charge running from the year the compensation was first deferred.8Office of the Law Revision Counsel. 26 US Code 409A – Inclusion in Gross Income of Deferred Compensation
The safest structure is to fit the “short-term deferral” exception: if the payment is made within two and a half months after the end of the tax year in which the right to payment is no longer contingent, 409A doesn’t apply. Earn-outs paid to sellers with no continuing employment relationship also fall outside 409A because the payment is purchase consideration rather than compensation. Getting the compensation-versus-purchase-price line wrong exposes the seller to the 20% penalty and back-interest on top of the regular tax.
Forms to File
Form 6252 for the Seller
Sellers reporting contingent payments under the installment method file Form 6252 each year a payment comes in. The form asks whether the total selling price can be determined by the close of the tax year, which is the pivotal question for a contingent sale.9Internal Revenue Service. Form 6252, Installment Sale Income When it can’t, the seller follows the regulatory basis recovery rules described above and reports accordingly.10Internal Revenue Service. Publication 537 (2025), Installment Sales
Form 8594 for Both Sides
In an applicable asset acquisition, both buyer and seller file Form 8594 with the return for the year of sale, reporting how the total purchase price is allocated across seven asset classes running from cash and near-cash items through goodwill. When a later contingent payment increases the total purchase price, the affected party files an updated Form 8594 for that year showing the revised allocation.11Internal Revenue Service. Instructions for Form 8594
Buyer and seller must use consistent allocations. When they don’t match, the IRS notices the discrepancy on cross-reference, and the mismatch will likely draw scrutiny on both returns.