Do I owe tax on an earnout before I receive the money?

Not on the earnout itself. The installment method of IRC §453 recognizes gain as payments come in, so an unpaid earnout produces no income. What it does do is raise the gain on the cash you already received, because Treas. Reg. §15a.453-1(c)(2) allocates your basis across the stated maximum selling price. A $6,000,000 closing payment on a $9,000,000 maximum recovers only 20% of the price as basis, not the 30% the actual proceeds would support.

Can I amend my earlier return if the earnout never pays out?

No. The unrecovered basis becomes a capital loss in the year the right to the contingent payments expires, not a correction to the year of sale. IRC §1211(b) then limits the deduction to $3,000 a year against ordinary income, and §1212(b) carries the rest forward indefinitely with no carryback for individuals. The practical fix is to realize other capital gains in that year so the loss has something to offset.

Is an earnout capital gain or ordinary income?

The gain portion takes the character of the asset sold, so an earnout on a sale of S corporation stock held more than a year is long-term capital gain. Two slices come out of that. Imputed interest under IRC §483 is ordinary income on every payment due more than six months after the sale, and any part of the earnout the IRS successfully recharacterizes as compensation is ordinary income with employment taxes attached.

Will calling an earnout purchase price instead of compensation trigger an audit?

The structure is ordinary and defensible. What draws examination is a mismatch between the label and the facts, mainly an earnout a departing shareholder forfeits by leaving. In Muskat v. United States, 554 F.3d 183, the First Circuit held the seller to the characterization written into his own agreement, which cuts both ways: a clean agreement is strong evidence and a sloppy one is fatal. Pay market salary separately and tie the earnout to business results, not to attendance.

What happens if my earnout has no cap and no end date?

You land in the worst tier of Treas. Reg. §15a.453-1(c). With neither a stated maximum selling price nor a fixed payment period, §15a.453-1(c)(4) recovers basis in equal annual increments over 15 years from the date of sale, and the regulation says these arrangements get close scrutiny over whether a sale occurred at all or the payments are really rent or royalty income. Put a ceiling or a term in the agreement. Both is better.

The Journal / Business Tax

Earnout Tax Treatment When Selling a Business and the Stranded Basis Trap.

By Ewan Morkel, EASeptember 7, 20266 min read

An earnout that never pays still spends your basis. IRC §453 allocates it across the maximum price, so a $3,000,000 earnout that comes in at zero reports $600,000 of gain you never had, and the offsetting loss takes 200 years to deduct.

Small business owner using a laptop at his desk

A founder sells a software company in December 2026 for $6,000,000 in cash plus up to $3,000,000 more if the business hits three years of revenue targets. It misses all three. The economics are plain: $6,000,000 collected against a $1,800,000 basis is $4,200,000 of gain. The 2026 return reported $4,800,000. Earnout tax treatment when selling a business is what produced the extra $600,000, and it takes 200 years to unwind.

The default

You are on the installment method whether you picked it or not.

§453(b)(1) defines an installment sale as a disposition where at least one payment lands after the close of the year of sale, and §453(a) makes the method the default. An earnout is exactly that. You get out only by electing out under §453(d), by the due date of the return including extensions, and §453(d)(3) makes that election revocable only with the Secretary's consent. §453(k)(2) shuts the method off entirely for stock or securities traded on an established securities market.

Electing out is rarely the escape it sounds like. Reg. §15a.453-1(d)(2)(iii) treats a contingent obligation's value as not reasonably ascertainable only in rare and extraordinary cases, and floors that value at the fair market value of the property sold less the other consideration received. Electing out generally means valuing the earnout right and paying tax on it in year one, on money that may never arrive.

The math

Earnout tax treatment when selling a business starts with the basis allocation.

Every installment payment splits between return of basis and gain by a gross profit ratio: gross profit divided by the contract price. With an earnout, nobody knows the contract price. Reg. §15a.453-1(c) answers that in three tiers.

A stated maximum selling price. If the most the agreement can pay is determinable at the end of the year of sale, that is the selling price, computed by assuming every contingency resolves in the way that maximizes it. Almost every earnout lands here.
A fixed period but no maximum. Basis comes back in equal annual increments over the years payment may be received.
Neither one. §15a.453-1(c)(4) spreads basis over 15 years from the sale date, and warns that these arrangements get close scrutiny.

Tier one is the one that bites. Assuming every contingency resolves in your favor inflates the denominator of the gross profit ratio and pushes basis onto payments that may never show up.

A $6,000,000 closing payment, a $3,000,000 earnout, and nothing earned.

Cash at closing, December 2026: $6,000,000
Maximum earnout, measured over 2027 through 2029: $3,000,000
Stated maximum selling price under Reg. §15a.453-1(c)(2): $9,000,000
Basis in the stock: $1,800,000
Gross profit ratio: 80%
Gain reported on the 2026 closing payment: $4,800,000
Basis recovered in 2026: $1,200,000
Earnout actually paid: $0
Economic gain on the whole deal: $4,200,000
Gain reported in excess of economic gain: $600,000
Federal tax on that excess at 23.8%: $142,800
Unrecovered basis, a capital loss in 2029: $600,000
Years to deduct that loss at $3,000 a year: 200

Tax year 2026 for the closing payment. Assumes a sale of S corporation stock for cash with no liabilities assumed, so the contract price equals the $9,000,000 stated maximum selling price, and selling expenses are ignored. Federal only, at the 20% top long-term capital gains rate, which starts at $613,700 of taxable income on a joint return for 2026 under Rev. Proc. 2025-32, plus the 3.8% net investment income tax under IRC §1411. IRC §1411(c)(4) can reduce or eliminate that 3.8% for a shareholder who materially participates, in which case the tax on the overstated gain is $120,000 rather than $142,800. No state income tax. The 200 years assumes no other capital gains in 2029 or later, so the loss runs off at the $3,000 annual limit of IRC §1211(b) with an indefinite carryforward under IRC §1212(b).

Two details soften that and neither one fixes it. When the maximum is reduced, by amendment or by a supervening event like the buyer's bankruptcy, Reg. §15a.453-1(c)(2) recomputes the gross profit ratio for payments received in or after the year of the reduction. That helps when the earnout pays something. Here there is no later payment for the better ratio to land on. And the loss is capital: IRC §1211(b) caps the deduction against ordinary income at $3,000 a year, §1212(b) carries the rest forward indefinitely, and individuals get no carryback.

The fix

An alternative basis recovery method, and the ruling it requires.

Reg. §15a.453-1(c)(7)(ii) allows an alternative method of basis recovery, but it takes a private letter ruling requested before the due date of the return, including extensions, for the year of sale. The showing is specific: a reasonable method of ratably recovering basis, and a reasonable conclusion, supported by verifiable sales and profit data, that basis will come back at twice the rate the normal rule allows. Worth the fee on a large deal, not on a small one.

The cheaper fix is upstream. The stated maximum is a drafting choice. A $3,000,000 ceiling nobody expects to hit costs you basis allocation for nothing, so an earnout sized to what the business will plausibly do produces a smaller denominator and a smaller year-one gain. That is a conversation with your attorney, not with me in March.

The interest

Part of every earnout payment is ordinary income.

An earnout right is generally not a debt instrument, because nothing is unconditionally owed, so the original issue discount rules of §1274 do not reach it. IRC §483 does. It catches any payment on account of a sale due more than six months out, under a contract where some payments are due more than a year out and there is total unstated interest.

Treas. Reg. §1.483-4 computes the split using the mechanics of §1.1275-4(c). Each contingent payment is principal to the extent of its present value, discounted back to the sale date at a test rate drawn from the applicable federal rates the IRS publishes monthly, most recently Rev. Rul. 2026-17 for September 2026. The rest is interest, taxed as ordinary income. On a payment three years out at a 5% test rate, about 13.6% of it is interest, a 17 point rate difference on that slice.

The recharacterization

The earnout that is really a paycheck.

Condition the earnout on staying employed and you have handed the IRS its argument that the money is compensation. That is ordinary income at up to 37% for 2026 plus employment taxes: 6.2% Social Security on wages up to the $184,500 wage base for 2026, 1.45% Medicare with no cap, and another 0.9% on wages above $200,000, with the employer share on top. A payment you priced at 23.8% can land north of 40%.

The paperwork usually decides it, and it decides against the seller. In Muskat v. United States, 554 F.3d 183, decided by the First Circuit on January 29, 2009, the seller reported $1,000,000 of covenant-not-to-compete money as ordinary income and then amended to call it capital gain. The court applied the Danielson rule and held him to the allocation in his own agreement.

Three habits keep an earnout on the purchase price side: pay a market salary for post-closing work under a separate employment agreement, tie the earnout to business results rather than continued service, and pay it pro rata to every selling shareholder. Expect resistance, because the buyer's tax interest runs opposite to yours. Compensation is deductible now. Purchase price gets amortized over what is left of the 15-year period under §197.

Two mechanics. The §453A interest charge applies only where the aggregate face amount of installment obligations outstanding at year end exceeds $5,000,000, so a $3,000,000 earnout does not trigger it and a $6,000,000 one does. Report the sale on Form 6252, and in an asset deal the Form 8594 allocation has to match the buyer's, the same discipline that makes a personal goodwill allocation hold.