Installment Sale vs Cash Sale: The After-Tax Math

The core trade: one big tax year, or many small ones

In a cash sale, the whole gain lands on one return. For a large sale that usually means the 20% federal capital gain rate, the 3.8% net investment income tax, and the top state brackets. In a Section 453 installment sale, also called seller financing, you take a down payment and a note, and each principal payment carries its share of the gain. Same total gain, spread over the years you choose. Our guides to installment sale tax and seller financing taxes cover the mechanics; this page is the head-to-head math.

Worked example: the same $2 million sale, cash vs a 10-year note

Assumptions (engine run): land held for investment sold in 2026 for $2,000,000 with an adjusted basis of $500,000, so the gain is $1,500,000 and the gross profit percentage is 75%; no depreciation; selling costs ignored. Married filing jointly with $120,000 of other ordinary income each year, living in a state with no income tax. Note option: $400,000 down and a $1,600,000 note at 6% for 10 years, level annual payments of $217,389 starting in 2027; 6% is above every October 2026 applicable federal rate (mid-term 4.61%, long-term 5.22%, Rev. Rul. 2026-19). Tax is the extra federal income tax plus net investment income tax the sale causes, from the installmentsalecalculator engine, with 2026 federal tables held flat for later years. The tax column covers the gain only.

The note lowers the federal tax on the same gain by $97,457 in this example, because almost every year's slice stays in the 15% bracket instead of reaching 20%. For a California resident with the same facts, the gain tax including California falls from $507,290 to $386,180 (see California installment sale tax). To test your own price, basis and terms, run your numbers.

Time value: why deferral is worth more than the totals show

A dollar of tax paid in 2036 costs less than a dollar paid in April 2027. Discounting each year's tax on the gain at 5%, the note's $247,803 is worth $199,749 in today's money, against $345,260 paid up front on the cash sale. Meanwhile the money you would have sent the IRS stays in the note, earning 6% from the buyer.

Two fair adjustments. First, the $573,887 of interest is taxable income; the engine puts federal tax on that interest, on its own, at $113,325 over 10 years. Second, a cash seller would invest the after-tax proceeds and earn taxable income too. The honest comparison is after-tax wealth at the end, at the same investment return, with the note's credit risk priced in. That is what the full analysis models.

Is seller financing a good idea?

It is a good idea when four things line up:

• The gain is large relative to your normal income, so a single year would push it into the top brackets.
• You want income more than a lump sum, and do not need the full proceeds for a purchase or debt payoff.
• The buyer is creditworthy, puts real money down, and accepts first-position security and standard default terms.
• Recapture is modest, since depreciation recapture is taxed in the year of sale regardless of the note.

It is a poor fit when you need the cash now, the buyer cannot show the ability to pay, the note would sit behind a bank loan, or most of the gain is recapture. Sellers with notes over $5 million should also price in the Section 453A interest charge. Selling to family has its own rules; see related-party installment sales.

Seller financing pros and cons

Pros

• Tax on the gain spread over the note, often at lower brackets and lower total tax.
• Interest income at a rate you negotiate, at or above the applicable federal rate.
• A wider pool of buyers and often a better price or terms.
• Faster closing without waiting on a bank's underwriting.
• The option to elect out and report everything in year one if that turns out better.

Cons

• Buyer credit risk; a default means legal costs and taking the property back. See buyer default and repossession.
• Less liquidity: selling or pledging the note accelerates the deferred gain.
• Depreciation recapture is still taxed in year one.
• Inflation erodes fixed payments; a rate set today may look low in later years.
• Unpaid notes at death carry income tax to heirs with no basis step-up.

How to protect the note

Ask for at least 20% down, record a first-position deed of trust or mortgage (or a UCC lien on business assets), get a personal guarantee from the owners of an entity buyer, require escrow for property taxes and property coverage, and write in acceleration, due-on-sale, a short cure period and annual financial reporting. A seller who sets those terms at the table is rarely the one forced to foreclose.

How Hans helps

The $5,000 Big Sale Tax Analysis models the cash sale and the installment sale side by side with a 1031, an Opportunity Zone investment and the other deferral paths, year by year and after tax, with a written recommendation. Get the full Big Sale Tax Analysis. For other head-to-heads, see 1031 vs installment sale.

Get the full Big Sale Tax Analysis

Frequently asked questions