Arm’s Length Transactions: Tax Rules and Mortgage Limits

An arm’s length transaction is a deal between two parties who act independently, on their own behalf, at a price the open market would produce. The concept matters because the IRS, mortgage lenders, courts, and auditors all use it as a benchmark: if a sale between related people or affiliated companies doesn’t meet the standard, the price can be recharacterized as a gift, losses can be disallowed, penalties of 20% or 40% can be added to any tax underpayment, and in some situations the transfer can be reversed outright.

What Makes a Transaction Arm’s Length

Two conditions have to hold. The parties act independently, and neither side has leverage that comes from a personal relationship or shared ownership. A willing buyer and a willing seller meet in an open market, both with access to the same information, and either can walk away.

Federal tax regulations phrase the standard in terms of outcome: a transaction between related parties is arm’s length only if the result matches what unrelated parties would have reached under the same circumstances.¹ When a deal falls short of that, regulators treat the stated price with suspicion and may substitute what they believe the correct arm’s length price should have been.

Who Counts as a Related Party

Certain relationships automatically flag a deal for closer scrutiny. Section 267 of the Internal Revenue Code identifies the main categories the IRS treats as related.²

Family members: spouses, siblings, parents, children, and in-laws. A house sold from parent to child at a discount is the textbook case.
An individual and a corporation in which that individual owns more than 50% of the stock.
Controlled corporate groups, including a parent and its subsidiary, or two subsidiaries under the same parent.
Trusts and their grantors, fiduciaries, and beneficiaries.
An estate and a beneficiary of that estate.

Accounting standards use a broader definition that also captures anyone with significant influence over a company and key management personnel and their close family.³

How to Prove the Price Is Fair

Related parties can still transact at arm’s length. They just need to show the price would hold up in the open market.

Independent appraisal is the most common method. A qualified third party examines the asset, reviews comparable sales, and assigns a value based on what an unrelated buyer would pay. For real estate, the appraiser adjusts nearby sales for differences in size, condition, and location. The written appraisal creates a paper trail that the IRS, lenders, and courts will accept as evidence.

Competitive bidding does similar work. Exposing an asset to multiple potential buyers through an open solicitation lets the market set the price through actual competition, and the final number carries built-in credibility.

For companies moving goods, services, or intellectual property between affiliates, Treasury regulations require selecting whichever pricing method produces the most reliable measure of an arm’s length result, sometimes called the best method rule. Approved methods include comparing the transaction to similar deals between unrelated companies, analyzing the cost of producing goods plus a normal profit margin, or benchmarking the controlled company’s profits against comparable independent companies.¹

Tax Consequences When the Price Is Off

The Discount Is Treated as a Gift

When property changes hands for less than full value, the gap between the sale price and fair market value is a gift for tax purposes. The statute is direct: if you transfer property for less than adequate consideration, the excess value counts toward your taxable gifts for the year.⁴ Sell a $400,000 house to your daughter for $300,000, and the IRS views the $100,000 discount as a gift.

The first $19,000 per recipient per year is covered by the annual gift tax exclusion for 2026 and requires no filing.⁵ Anything above that threshold requires Form 709 and reduces your lifetime exemption. For 2026, that exemption sits at $15,000,000, raised by the One, Big, Beautiful Bill signed into law on July 4, 2025.⁶ Most people won’t owe actual gift tax until cumulative lifetime gifts pass that amount, but the filing obligation starts much earlier.

You Cannot Deduct a Loss

Section 267 flatly prohibits deducting a loss on a sale to a related party. This applies across every category on the related-party list, from family to controlled corporations to trusts.² It’s one of the most commonly missed rules in this area. People sell depreciated stock or property to a family member, claim the loss, and face a disallowance on audit. The same sale to an unrelated buyer would have produced a fully deductible loss.

Transfer Pricing Between Affiliated Companies

When affiliated businesses trade with each other, the IRS has broad authority to rewrite prices that don’t reflect what unrelated companies would charge. Section 482 lets the government reallocate income and deductions among businesses under common control whenever the reported figures don’t clearly reflect each entity’s actual income.⁷ The rule targets profit-shifting to low-tax jurisdictions, but it applies just as fully to domestic arrangements between commonly controlled companies.

IRS Penalties for Mispricing

A wrong price on a related-party deal can trigger a penalty stacked on top of the additional tax owed. There are two tiers.

A substantial valuation misstatement adds 20% to the underpayment. For transfer pricing, this applies when the price claimed is 200% or more of the correct arm’s length price, or 50% or less of it. It also applies when the net transfer pricing adjustment for the year exceeds the lesser of $5,000,000 or 10% of the taxpayer’s gross receipts.⁸

A gross valuation misstatement doubles the penalty to 40%. The thresholds are steeper: the claimed price must be 400% or more of the correct amount (or 25% or less), or the net adjustment must exceed the lesser of $20,000,000 or 20% of gross receipts.⁸ The penalty runs against the underpayment amount, not the full tax bill, but on large transactions the numbers move quickly.

Mortgage Rules for Related-Party Home Sales

Lenders treat non-arm’s length real estate sales cautiously because the agreed price may not reflect what the property is actually worth. An inflated price between family members can leave the lender secured against less collateral than the loan balance.

FHA Loans

FHA classifies any sale between parties with a family or business relationship as an “identity of interest” transaction. The maximum loan-to-value ratio drops to 85%, meaning the buyer needs 15% down instead of the standard 3.5%.⁹ On a $300,000 purchase, that shifts the down payment from $10,500 to $45,000.

One exception: if the buyer has rented the property for at least six months before signing the purchase contract, the 85% cap can be waived. The buyer needs a lease or other written proof of occupancy.⁹

Conventional Loans

Fannie Mae allows non-arm’s length purchases of existing properties without the same LTV cap that FHA imposes. If the buyer has a relationship or ownership interest with the builder, developer, or seller of a newly constructed home, Fannie Mae will only purchase the loan when the property is the buyer’s principal residence. Second homes and investment properties are excluded from related-party new construction deals.¹⁰ Expect lenders to require a full appraisal and to look harder at comparable sales than they would for a transaction between strangers.

When a Deal Can Be Unwound

Selling property to a relative or affiliated company at a discount isn’t only a tax problem. If you later file for bankruptcy or face collection from creditors, the transaction can be reversed entirely.

Under the Bankruptcy Code, a trustee can avoid any transfer made within two years before the bankruptcy filing if the debtor either intended to defraud creditors or received less than reasonably equivalent value while insolvent.¹¹ The two-year window is the federal baseline. Many states have adopted the Uniform Voidable Transactions Act with a four-year look-back, and some allow creditors to reach further under certain conditions.

Intent isn’t required. A transfer can be unwound on purely financial grounds if the property sold for less than its worth and the seller was insolvent at the time or became insolvent because of the sale. A below-market price combined with a sale to an insider matches the pattern courts call badges of fraud, and a related-party sale at a discount checks two of the most common ones at once.¹¹

Disclosure Requirements for Businesses

Companies that engage in related-party transactions must disclose them in their financial statements whether or not the transactions were at arm’s length. Under U.S. accounting standards (ASC 850), the disclosure covers the nature of the relationship, a description of the transactions, dollar amounts for each reporting period, and any balances owed. International standards under IAS 24 add a notable restriction: a company can only claim its related-party transactions were on arm’s length terms if those terms can actually be substantiated with evidence.³

The IRS enforces its own documentation standard through Section 482. Companies with cross-border related-party transactions need contemporaneous transfer pricing documentation showing that intercompany prices were set using an approved method and that the chosen method produces the most reliable measure of an arm’s length result.¹ Without that documentation, a company has no defense against the valuation misstatement penalties.

1
eCFR. 26 CFR 1.482-1 – Allocation of Income and Deductions Among Taxpayers
2
Office of the Law Revision Counsel. 26 USC 267 – Losses, Expenses, and Interest With Respect to Transactions Between Related Taxpayers
3
IFRS Foundation. IAS 24 Related Party Disclosures
4
Office of the Law Revision Counsel. 26 USC 2512 – Valuation of Gifts
5
Internal Revenue Service. Frequently Asked Questions on Gift Taxes
6
Internal Revenue Service. What’s New – Estate and Gift Tax
7
Office of the Law Revision Counsel. 26 USC 482 – Allocation of Income and Deductions Among Taxpayers
8
Office of the Law Revision Counsel. 26 USC 6662 – Imposition of Accuracy-Related Penalty on Underpayments
9
U.S. Department of Housing and Urban Development. HUD 4155.1 – Transactions Affecting Maximum Mortgage Calculations
10
Fannie Mae. Purchase Transactions
11
Office of the Law Revision Counsel. 11 USC 548 – Fraudulent Transfers and Obligations