By the time a buyer and seller agree on a price, most owners think the tax outcome is settled. It isn’t. Two deals with identical headline numbers can produce lifetime tax bills that differ by six figures, because the tax code doesn’t tax the price; it taxes the payments, and when those payments arrive is a design choice. Seller financing, deferred purchase price, and earnouts all push cash into future years, and Section 453 of the tax code decides how the gain follows the cash.
This article covers the machinery: how the installment method allocates each payment between basis and gain, what income can’t be deferred no matter what the contract says, the $5 million threshold where the IRS starts charging you interest on your own tax deferral, how earnouts are taxed when nobody knows the final price, and the situations where electing out of installment treatment and paying all the tax in year one is the smarter move. The exit timeline and the estate window that closes at the letter of intent are covered in their own articles; this is the deal-structure layer that sits between them.
The Installment Method: Gain Follows the Cash
Sell for at least one payment after the year of sale and you have an installment sale by default. No election, no special form beyond reporting on Form 6252. Each payment you receive is split using the gross profit ratio: gross profit divided by contract price. That fraction of every payment is taxable gain; the rest is tax-free return of basis. Interest on the note is taxed separately as ordinary income, and if the contract doesn’t state adequate interest, the tax code imputes it, converting some of your “price” into interest whether you like it or not.
A worked example that carries through this article. You sell your business for $6,000,000 with $1,500,000 of basis: $4,500,000 of gross profit, a 75% gross profit ratio. The buyer pays $1,200,000 at closing and $1,200,000 in each of the next four years. Each payment carries $900,000 of long-term gain (75% of $1,200,000) and $300,000 of basis recovery. Five years, $900,000 of gain per year, instead of $4,500,000 in one.
Why that spreading matters under 2026 rates. For a married couple, the 20% capital gains rate begins at $613,700 of taxable income; below that, long-term gain rides at 15%. Take the whole $4,500,000 in one year (assume $200,000 of other taxable income and Texas residency, so no state tax): roughly $413,700 of the gain fills the rest of the 15% bracket ($62,055), the remaining $4,086,300 is taxed at 20% ($817,260), and net investment income tax adds 3.8% on nearly all of it (about $169,100). Call it $1,048,000. (The example assumes the gain is subject to NIIT, which fits C corporation stock or a passive owner; gain on nonpassive business assets sold by an active S corporation or partnership owner is generally excluded from net investment income, so an active owner may owe little or none of that 3.8% layer.) Spread the same gain over five years and each year’s $900,000 of gain fills the 15% bracket first, pays 20% only on the excess, and triggers a smaller NIIT bite: about $191,600 per year, $958,000 over five years. The structure alone keeps roughly $90,000, before counting the time value of paying later, and the effect grows when the seller’s other income drops after the sale, which it usually does. (The comparison isolates the gain; the installment seller also collects interest on the note, taxable as ordinary income, which the lump-sum seller never receives.)
One more place this machinery shows up without being named: a seller-financed buyout under a buy-sell agreement is an installment sale, so a partner’s exit funded from the company’s cash flow runs through this same machinery, a point that connects to our article on buy-sell agreements after Connelly.
What Cannot Ride the Installment Method
The contract can defer cash; it cannot defer everything the tax code wants now. Four categories come out of the installment method regardless of payment schedule, which is why the purchase price allocation negotiated with the buyer matters as much as the payment schedule itself.
Depreciation recapture is taxed entirely in the year of sale. All Section 1245 and Section 1250 ordinary-income recapture is recognized at closing even if you haven’t received a dollar beyond the down payment. (Unrecaptured Section 1250 gain, the 25%-rate slice on straight-line real estate depreciation, is different: it does ride the installment method, spread across the payments.) An asset sale of an equipment-heavy business can produce a year-one tax bill larger than the year-one payment, which is a cash flow trap, not just a tax one.
Receivables and inventory produce ordinary income in the year of sale in an asset deal; they are not installment-eligible property.
Publicly traded stock can never use the installment method, which is why this whole toolkit belongs to private-business sales.
Losses don’t spread either; the method applies to gain.
Related-party sales carry their own tripwires. Sell on installment to a related party (family, controlled entities) and two rules wait: if the related buyer resells within two years, your deferred gain accelerates as if you’d been paid; and the installment method is unavailable altogether for depreciable property sold to a related party. Family succession deals, which are exactly where seller financing feels most natural, need both rules checked before the note is drafted.
Goodwill, going-concern value, and most intangibles, typically the largest slice of a service or professional business, are installment-eligible capital gain, which is exactly why buyers and sellers fight over allocation: the buyer wants price on fast-depreciating assets, and every dollar that lands there is a dollar the seller may be taxing at ordinary rates in year one.
The $5 Million Line: Section 453A’s Interest Charge
Deferral this useful has a meter on it. When your installment obligations from sales over $150,000 exceed $5,000,000 of face value outstanding at the end of the year of sale (measured per seller, and each spouse counts separately against their own share; confirm the joint-return application with your CPA), Section 453A charges interest on a slice of your deferred tax, at the IRS underpayment rate, and the interest is nondeductible. The slice is set once, in the year of sale: the applicable percentage equals the face amount over $5,000,000 divided by the total face amount, and that fixed percentage applies to the deferred tax on whatever balance remains outstanding every year until the note is paid off, even after the balance itself falls below $5,000,000. It converts free deferral into a nondeductible loan from the Treasury, at a rate you don’t control, for the life of the note.
Two design implications. First, the threshold is tested at the end of the year of sale against the balance still outstanding, so payment schedules can be built around it: in our $6,000,000 example, $1,200,000 paid at closing leaves $4,800,000 outstanding on December 31, under the line, and no interest charge ever applies. A $10,000,000 deal with 10% down leaves $9,000,000 outstanding at year end, locking in an applicable percentage of $4,000,000 ÷ $9,000,000, about 44%, that follows the note for its entire life. Second, the $5,000,000 test applies per person, so a business owned 50/50 by two spouses, or by two partners, measures each seller’s obligations separately. This is a structuring conversation for the year before the letter of intent, not the week after closing.
One more rule in the same section with teeth: pledge an installment note as collateral for a loan and the loan proceeds are treated as a payment on the note. You cannot defer the tax and borrow against the deferred value at the same time.
Earnouts: Taxing a Price Nobody Knows Yet
Earnouts tie part of the price to the business’s future performance, and they are everywhere in service-business exits where the buyer worries the revenue walks out with you. Tax law handles the unknown price with three regimes.
Stated maximum price. If the contract caps the earnout, the tax code assumes you’ll collect the maximum: basis is recovered using the cap as the contract price, and if the earnout falls short, you claim the shortfall as a loss when the cap lapses. Front-loaded gain, back-loaded relief.
Fixed period, no maximum. If payments run for a defined term with no cap, basis is recovered ratably over the term.
Neither. No cap and no fixed term is the tax code’s least favorite deal; basis recovers over 15 years, and the arrangement invites IRS scrutiny of whether a sale happened at all.
Two traps sit inside every earnout. The first is character: an earnout contingent on the seller’s continued employment is compensation in the IRS’s eyes, taxed at ordinary rates plus payroll tax, no matter what the purchase agreement calls it. If the earnout is truly purchase price, it should be payable whether or not you stay, with any employment paid for separately at market rates. The second is imputed interest: deferred payments without stated interest get a slice recharacterized as ordinary interest income under the imputed-interest rules, quietly shrinking the capital gain everyone modeled. And beneath both tax traps sits the practical one: an earnout is paid on the performance of a business you no longer run, under pricing, staffing, and service decisions the buyer now makes, so the tax analysis of an earnout should always be paired with a hard look at how achievable the targets are and what happens to the payments if the buyer ends your involvement early.
When Paying All the Tax Now Is the Better Deal
The installment method is the default, not a mandate; you can elect out on a timely filed return and recognize the entire gain in the year of sale, and the election is effectively irrevocable. Reasons this is sometimes right:
Expiring or expired attributes. Large capital loss carryforwards, charitable carryforwards near their five-year limit, or an NOL that offsets the gain make year-one recognition cheap. A seller with $2,000,000 of loss carryforwards may prefer $4,500,000 of gain today against those losses over $900,000 a year against nothing.
A uniquely low-income year. A seller retiring into the sale year with little other income may find the brackets, and even the 0% capital gains bracket for a modest deal, more valuable now than spread.
Expected rate or residency changes. Gain recognized on the installment method is taxed under the law, and in the state, of the year each payment arrives. A seller planning to move from Texas to a high-tax state wants the gain recognized while a Texan; one moving the other direction wants the opposite. The same logic applies to expected federal rate changes, in both directions.
Section 453A costs. Above the $5,000,000 line, the interest charge erodes the deferral benefit, and electing out (or restructuring payments) can win the arithmetic.
QSBS makes the decision case-specific. For C corporation stock qualified under Section 1202, excluded gain flows through payment by payment, and the exclusion percentage is fixed by your holding period on the sale date. But the per-issuer exclusion cap is tested year by year, so a note that trickles gain across many years can strand exclusion capacity that a year-one sale would have captured, and for stock acquired after July 4, 2025, the interaction with the new tiers and caps makes sequencing matter even more. Electing out and banking the full exclusion in the year of sale is sometimes the winner, which is exactly the kind of thing to model rather than assume. The framework is in our Section 1202 article.
Default risk belongs in this decision too, because an installment seller is a lender. Until paid, you hold the buyer’s credit, usually secured by the business you no longer control. Security agreements, personal guarantees, and standby letters of credit preserve installment treatment; cash parked in an unrestricted escrow generally does not, because the constructive receipt rules treat money set aside for you with no substantial restrictions as payment received, and a note secured directly or indirectly by cash or its equivalent is treated the same way. (The routine indemnity holdback escrow in most purchase agreements is different: escrow subject to substantial restrictions, released only if no claims arise, is generally not payment until released.) The lender’s-eye diligence on your own buyer is not paranoia; it’s the price of the deferral.
The Packaged Versions: Where Deferral Products Go Wrong
Because the installment method’s two real drawbacks are buyer credit risk and locked-up cash, an industry exists to sell business owners products that promise the deferral without the drawbacks. They deserve their own warning label, because the differences among them are large.
Monetized installment sales promise the deferral and the cash at the same time: an intermediary buys your business on a note, resells it to your real buyer for cash, and a related lender hands you a “loan” of roughly the sale proceeds. The IRS has stated in published analysis that it considers the structure defective on multiple independent grounds (the intermediary is not a real buyer, the loan is not a real loan, and a note secured by the cash is payment now), and in 2023 it proposed regulations designating these transactions and anything substantially similar as listed transactions, the tax code’s most radioactive reporting category. The IRS has featured these schemes on its Dirty Dozen list, and the Justice Department has gone to court against promoters. Commenters on the proposed regulations have warned that the “substantially similar” language is broad, which is one more reason a clean two-party note should look nothing like the intermediary structure. Getting the deferral and the money simultaneously is precisely the thing Section 453 does not allow, and no packaging fixes that.
Deferred sales trusts route the sale through a promoter-controlled trust that owes you an installment note. The structure has never been blessed by the IRS, the promoters’ materials are proprietary, and the public record includes a state securities regulator’s enforcement action against a DST trustee and an IRS suit in federal court to enforce a summons on DST transactions. The core problem is structural: you cannot control the trust without losing the tax treatment, so the sale proceeds sit with a trustee who owes you only the note payments, and your recourse is limited to the note. The credit risk you were escaping didn’t disappear; it moved to a party you chose not to vet.
Structured installment sales are the conservative cousin: the deferred payments are funded through an annuity from a large life insurer via a nonqualified assignment, resting on decades-old revenue rulings that permit substituting the obligor. The seller trades the buyer’s credit for an insurance company’s, which is usually a real improvement, at the cost of locking the payment schedule permanently. It has not been formally blessed by the IRS either, but it does not fight the statute the way the first two do.
The test we lean toward for any of these: if the pitch promises the tax deferral and the use of the money at the same time, the structure is fighting Section 453 rather than using it. A plain two-party installment note, underwritten carefully and sized against the projection, doesn’t need a wrapper.
We lean toward treating the payment schedule as an output of the multi-year tax projection rather than a term the buyer proposes and the seller accepts. Model the gain against each year’s brackets, NIIT, the 453A line, IRMAA if Medicare is near, and the seller’s post-sale income, and the right down payment percentage and note term usually announce themselves. The exit timeline article covers when this modeling happens (early); the estate article covers what must happen before the letter of intent; this is the piece in between, and it is negotiable in ways most sellers never test.
Common Questions
Is an installment sale something I elect?
No, it’s the default whenever at least one payment lands after the year of sale. The election runs the other way: you can elect out on a timely filed return (including extensions) and recognize all the gain in the sale year, and that election is effectively permanent once made.
Does the interest I receive on the note get capital gains treatment?
No. Each payment has up to three parts: return of basis (tax-free), gain (capital, at the gross profit ratio), and interest (ordinary income). If the note doesn’t charge adequate stated interest, the tax code imputes it, carving ordinary interest income out of what the contract called principal.
What happens if the buyer defaults and I take the business back?
Repossession is a taxable event with its own rules. For personal property and intangibles, which is most of a business (goodwill, equipment, an entity interest), your gain or loss is the value of what you get back, minus your remaining basis in the note, minus repossession costs, and the reacquired property takes a fair-market-value basis. Real property runs under a different, more forgiving rule that caps recognized gain roughly at cash received beyond gain already reported. Either way, you don’t unwind the prior years, and the practical answer is to underwrite the buyer like the lender you are becoming.
What if I die holding the installment note?
The note does not get a basis step-up. It’s income in respect of a decedent: your heirs report the same gain portion of each payment you would have, though they can deduct any estate tax attributable to the note. Canceling the note at death, including through a bequest to the buyer, triggers the deferred gain on your final return or in your estate. This is one of the few sale assets where dying doesn’t erase the tax, and it belongs in the estate conversation before the sale closes.
Can I use an installment sale for my S corporation or partnership interest?
Generally yes for the interest itself, but look-through rules apply: the portion of gain attributable to inventory, receivables, and depreciation recapture (“hot assets” in a partnership) is not installment-eligible and comes out as ordinary income in the year of sale. The clean version of the answer requires the entity’s balance sheet, not just the purchase agreement.
How is an earnout taxed?
If the earnout is genuinely contingent purchase price, it’s capital gain under the contingent-payment rules, minus any imputed interest. If it’s contingent on your continued employment, the IRS treats it as compensation at ordinary rates plus payroll taxes. The cleanest structures pay the earnout regardless of employment and compensate any post-sale work separately at market rates.