SIH Partners LLLP, Explorer Partner Corp., Tax Matters Partner v. Commissioner of Internal Revenue, 167 T.C. No. 8 (August 6, 2026)

In the highly structured world of corporate tax planning, practitioners often seek comfort in the mechanical safe harbors provided by the Treasury Regulations. The presumption is that if a transaction can be mathematically engineered to comply with a bright-line test, the taxpayer’s tax position is secure. However, the recent United States Tax Court decision in SIH Partners LLLP v. Commissioner, 167 T.C. No. 8 (August 6, 2026), serves as a stark reminder that subjective anti-abuse rules can completely override formal regulatory compliance.

In this case, the Tax Court examined a sophisticated dividend arbitrage transaction involving hundreds of millions of dollars in Swiss equities, a portfolio swap, and a pre-existing firm-wide hedge. While the taxpayer successfully engineered the transaction to comply with the mechanical “Substantial Overlap Test” under the portfolio rules of Treasury Regulation § 1.246-5(c)(1)(iii), the Court ultimately disallowed over $170 million in qualified dividend income (QDI) and more than $25 million in foreign tax credits (FTCs) by applying the broad, subjective “Anti-Abuse Rule” of Treasury Regulation § 1.246-5(c)(1)(vi). For CPAs and Enrolled Agents (EAs), the decision provides invaluable lessons on the limits of literal compliance and the rigorous standards the IRS and courts will apply to pre-transaction economic profit analyses.

Background and Facts of the Transaction

The taxpayer, SIH Partners LLLP (SIHP), is a Delaware limited liability partnership classified as a partnership for U.S. federal income tax purposes under the Tax Equity and Fiscal Responsibility Act of 1982 (TEFRA). SIHP operates through several wholly owned, disregarded entities, including CVI Holdings LLC (CVIH) and Capital Ventures International (CVI), an unlimited liability company organized under the laws of the Cayman Islands. All items of income, gain, loss, deduction, and credit from these entities were reported directly by SIHP.

SIHP and its affiliates are associated with Susquehanna International Group, LLP (SIG), a privately held global proprietary trading firm and prominent options and futures market maker. As part of its risk management, SIG has maintained a “Firm Hedge” since 1987. This Firm Hedge consists of unhedged short positions in major market indexes—specifically the S&P 500 index (SPX), the Russell 2000 ETF (IWM), and the China Large Cap ETF (FXI)—to mitigate the firm’s overall exposure to economic downturns. Historically, this Firm Hedge has lost between $1.25 billion and $2.5 billion, but it remained a core component of SIG’s risk management architecture.

Until 2010, the Firm Hedge was maintained in a prime brokerage account with Merrill Lynch, which required a 15% margin rate in cash or collateral. In 2010, Morgan Stanley approached SIG with a twofold proposal: first, to move the Firm Hedge to Morgan Stanley’s foreign-owned entities in exchange for a significantly lower margin rate of 6.5%; and second, to enter into a series of agreements that would structure a complex portfolio swap centered on four Swiss equities. The four Swiss equities selected were Nestle SA (NESN VX), Novartis AG (NOVN VX), Roche Holding AG (ROG VX), and Swisscom (SCMN VX) (collectively, the Swiss Equities).

The Transaction was structured from April 2010 through October 2013 as follows:

SIHP purchased the Swiss Equities through Credit Suisse and held them in long positions over their respective ex-dividend dates in its Morgan Stanley prime brokerage account.
Simultaneously, SIHP entered into a portfolio swap with Morgan Stanley that provided identical short positions in each of the Swiss Equities, as well as incorporating the short positions of the Firm Hedge (the SPX, IWM, and FXI indexes).

For the 2012 tax year, SIHP reported $170,764,863 in gross dividends received from the Swiss Equities, claiming this amount as qualified dividend income (QDI) under Internal Revenue Code (I.R.C.) § 1(h)(11). The dividends paid by the individual companies were:

Nestle SA: $64,871,330
Novartis AG: $45,005,029
Roche Holding AG: $55,968,147
Swisscom: $4,920,358

Under the terms of the portfolio swap, SIHP was obligated to pay Morgan Stanley a “substitute dividend” equal to approximately 78% to 80% of the gross dividends received on the long Swiss Equities. For 2012, SIHP transferred $130,175,828 in substitute dividends to Morgan Stanley, leaving SIHP with a net cash dividend of $40,589,035.

Additionally, the Swiss Federal Tax Authority (SFTA) imposed a mandatory 35% withholding tax on the gross dividends, resulting in $59,767,702 of taxes withheld. Under the U.S.-Switzerland Income Tax Treaty, nonresidents are eligible to file a reclaim request to recover 20% of the gross dividends, reducing the effective Swiss tax rate to 15%. SIHP timely filed reclaim requests with the SFTA for the 2010, 2011, and 2012 tax years, but the SFTA had not accepted or paid these claims at the time of the trial. On its 2012 tax return, SIHP reported a foreign tax credit (FTC) of $25,614,729, which represented the 15% net treaty rate on the gross dividends, before receiving any confirmation of the Swiss reclaims.

Following an audit, the IRS issued a Notice of Final Partnership Administrative Adjustment (FPAA) on December 5, 2019. The IRS:

Reduced SIHP’s reported QDI by $170,764,863 and reclassified the entire amount as ordinary dividend income.
Disallowed and reduced SIHP’s reported foreign tax credit by $25,614,729.

The IRS based its adjustments on I.R.C. § 246(c)(4) and the regulations thereunder, asserting that SIHP’s holding periods in the Swiss Equities were tolled because SIHP had systematically diminished its risk of loss by holding substantially similar or related property (SSRP) in the form of the offsetting short positions in the portfolio swap.

The Taxpayer’s Request for Relief and Key Arguments

SIHP petitioned the U.S. Tax Court challenging the FPAA, seeking a full restoration of the QDI classification and the $25,614,729 foreign tax credit. The taxpayer’s technical arguments were highly sophisticated and relied heavily on the literal application of Treasury Regulation § 1.246-5:

First, SIHP argued that the portfolio swap was a single, unitary position that reflected the value of a portfolio of stocks rather than individual positions. Under Treasury Regulation § 1.246-5(c)(1)(i), a “portfolio” is defined as any group of stocks of 20 or more unrelated issuers. Because the swap incorporated the SPX index (tracking 500 companies), IWM, and FXI, the underlying position clearly represented more than 20 unrelated issuers.
Second, the taxpayer asserted that under the “Substantial Overlap Test” of Treasury Regulation § 1.246-5(c)(1)(ii) and (iii), a portfolio position is treated as SSRP only if the position and the taxpayer’s stock holdings substantially overlap. Under this mechanical, bright-line test, a substantial overlap exists only if the Subportfolio’s fair market value is equal to or greater than 70% of the fair market value of the stocks represented in the position. On the relevant testing date of April 24, 2012, the overlap between SIHP’s long Swiss Equities and the short positions in the portfolio swap was mathematically calculated to be 64.38% (due to the dilutive effect of the multi-billion-dollar Firm Hedge short positions included in the swap). Because 64.38% is less than the 70% regulatory threshold, SIHP argued that the swap did not “substantially overlap” with the stock holdings, and therefore did not constitute SSRP under the safe harbor.
Third, SIHP argued that the general “Anti-Abuse Rule” of Treasury Regulation § 1.246-5(c)(1)(vi) did not apply. They advanced a narrow reading of the “Virtual Tracking Test” in subparagraph (A), arguing that because the regulation uses the disjunctive “or,” the phrase “changes in the value of the position” applies exclusively to portfolios, while “or the stocks reflected in the position” applies only to nonportfolios. They called Dr. Thomas J. Brennan (a Harvard Law professor) as an expert, who testified that the portfolio swap’s overall value did not “virtually track” the Swiss Equities’ value because the deviation exceeded 5%.
Fourth, SIHP argued that there were no “tax savings” under the second prong of the Anti-Abuse Rule, contending that statutory benefits like QDI and FTCs do not constitute “tax savings” within the meaning of the rule. Furthermore, they called Dr. Michael Cragg as an expert, who asserted that the transaction was entered into with an expected pre-tax economic profit of approximately $32 million once the economic and financing benefits of the Firm Hedge (estimated at $121 million) were properly valued.

The Substance-Over-Form Debate and the Substantial Overlap Test

The Commissioner’s threshold argument was a classic common law attack: the IRS invoked the substance-over-form doctrine, originally established in Gregory v. Helvering, 293 U.S. 465 (1935), and reemphasized in Frank Lyon Co. v. United States, 435 U.S. 561 (1978). The IRS argued that the court should look past the “portfolio” form of the swap and disaggregate it into its constituent parts. By isolating the Swiss Equities from the Firm Hedge, the IRS sought to treat the Swiss Equities as separate “Nonportfolio Positions” under Treasury Regulation § 1.246-5(c)(1)(v), which would immediately fail the SSRP test since the Swiss Equities were hedged at 100%.

The Tax Court’s analysis of the substance-over-form argument is one of the most critical aspects of this decision for tax professionals. Judge Weiler carefully reviewed the common law doctrine, noting that while the Commissioner regularly recharacterizes sham transactions,

“there has yet to be a case that outright holds tax-avoidance alone may nullify an otherwise Code-compliant and substantive set of transactions.”

The Court credited the testimony of the taxpayer’s expert, Dr. Luc Faucheux, who explained that it is standard industry practice for proprietary trading firms and market makers to place pre-existing firm hedges into portfolio swaps to optimize collateral and minimize overall financing costs. The Court determined that the swap was a conventional portfolio swap with standard commercial terms, and that SIHP’s chosen form matched its economic substance.

Crucially, the Court rejected the IRS’s attempt to use substance-over-form to bypass the highly specific regulations drafted by the Treasury:

“The substance-over-form doctrine does not ‘tak[e] a transaction entirely outside its statutory framework,’ but instead, ‘helps courts read tax statutes in a way that makes their technical language conform more precisely with Congressional intent.’”

The Court held that the regulations left no room for judicial disaggregation of a valid portfolio swap, stating:

“[W]e think it is far more appropriate to require both parties to turn square corners and to live with the end result of SIHP’s regulatory compliance.”

Applying the plain text of the regulations, the Court concluded that because the swap contained stocks of 20 or more unrelated issuers, the Portfolio Rules applied. Since the Subportfolio overlap was only 64.38% (well below the 70% threshold), the Court ruled in favor of the taxpayer on this issue:

“In sum, and relying upon the plain text of the regulation, we hold that the Transaction, consisting of a swap arrangement containing the Firm Hedge and the Swiss Equities, does not qualify as SSRP under the Substantial Overlap Test.”

Deconstructing the Anti-Abuse Rule

Although the taxpayer won the battle over the mechanical “Substantial Overlap Test,” they ultimately lost the war under the “Anti-Abuse Rule” of Treasury Regulation § 1.246-5(c)(1)(vi). This rule acts as an overriding catchall that can reclassify a position as SSRP even if the mechanical overlap test is satisfied.

The Anti-Abuse Rule is triggered if two conditions are met:

The Virtual Tracking Test: Changes in the value of the position (or the stocks reflected in the position) are reasonably expected to virtually track, directly or inversely, changes in the value of the taxpayer’s stock holdings (or a portion thereof and other positions).
The Tax Savings vs. Expected Profit Test: The position is acquired or held as part of a plan, a principal purpose of which is to obtain tax savings that are significantly in excess of the expected pre-tax economic profits from the plan.

In evaluating the Virtual Tracking Test, the Court rejected the taxpayer’s narrow, disjunctive reading of the regulation, clarifying that the rule does not distinguish between portfolio and nonportfolio positions:

“We read the regulation to be broad in application and determine Treasury intended for it to serve as a catchall for potential abuse.”

The Court also rejected Dr. Brennan’s mathematical assertion that “virtual tracking” required a correlation of 95% or higher (or a maximum 5% deviation). The Court noted that the regulation does not specify a rigid deviation standard. Because SIHP maintained identical, offsetting short positions in the Swiss Equities within the swap, there was a “100 percent hedge” with respect to those specific stocks. Thus, changes in the value of the short Swiss Equities in the swap were reasonably expected to virtually track the long Swiss Equities inversely.

In evaluating the Tax Savings vs. Expected Profit Test, the Court faced a classic battle of the experts regarding what constitutes “tax savings” and how to calculate “expected pre-tax economic profits.”

On the question of “tax savings,” the Court dismissed the taxpayer’s argument that statutory tax benefits should be excluded. Relying on the expert report of the IRS’s expert, Dr. Israel Nelken, the Court determined that the tax savings generated by the transaction (consisting of the QDI preferential rate differential and the claimed foreign tax credits) amounted to more than $25 million for the 2012 tax year.

On the question of “expected pre-tax economic profits,” the Court thoroughly dissected the internal analyses prepared by SIHP’s equity finance manager, Jeff Cohen (Cohen’s 2010 and 2012 Analyses), and the trial report of the taxpayer’s expert, Dr. Michael Cragg.

The Court found Dr. Cragg’s expected profit calculation of $32 million to be highly unreliable because it added a highly subjective $121 million “economic benefit” from the Firm Hedge, which the Court flatly rejected.
The Court emphasized that because of the 35% Swiss withholding taxes and the swap’s dividend ratio (requiring SIHP to pay 78% to 80% of gross dividends back to Morgan Stanley), the Swiss Equities transactions could not be profitable on an independent pre-tax basis.
The taxpayer’s own pre-transaction analyses (Cohen’s Analyses) were remarkably thin, failed to account for foreign currency transaction costs, and relied on the unrealistic assumption of an immediate 20% Swiss treaty reclaim despite the SFTA having never granted such reclaims for 2010 or 2011.

Accordingly, the Court accepted a realistic expected pre-tax profit range of $0 to $2.4 million (representing the high end of Cohen’s 2012 Analysis) with an expected pre-tax loss of up to $31 million on the low end (per Dr. Nelken’s calculations).

Comparing the two values, the Court found that the tax savings of over $25 million were “significantly in excess” of the expected pre-tax economic profits of $0 to $2.4 million. Consequently, the Court held that the Anti-Abuse Rule applied:

“We therefore determine the Anti-Abuse Rule of Treasury Regulation § 1.246-5(c)(1) is applicable to the Transaction and that, on the basis of the evidence presented, the Transaction fails to comply with the Anti-Abuse Rule. We hold that SIHP’s position in the Swiss Equities is SSRP.”

Application of the Law to the Facts and Final Conclusions

Once the Court determined that the Swiss Equities constituted SSRP under the Anti-Abuse Rule, the statutory consequences under I.R.C. § 246(c) and I.R.C. § 901(k) applied automatically:

Under I.R.C. § 246(c)(4)(C), the holding period of stock is reduced or tolled for any period in which the taxpayer has diminished its risk of loss by holding one or more positions in SSRP. Because SIHP was fully hedged via the portfolio swap, its holding period in the Swiss Equities was tolled for the entire duration of the Transaction. Consequently, SIHP failed to meet the 60-day holding period requirement of I.R.C. § 1(h)(11)(B)(iii)(I), rendering the $170,764,863 in dividends ineligible for preferential QDI treatment and reclassifying them as ordinary income.
The disallowance of the Foreign Tax Credit followed the same statutory logic. Under I.R.C. § 901(k)(1)(A), a taxpayer is denied a foreign tax credit for withholding taxes on dividends if the taxpayer does not meet a 15-day holding period requirement during a 31-day window surrounding the ex-dividend date. Crucially, I.R.C. § 901(k)(1)(B) explicitly provides that no credit is allowed to the extent that the recipient of a dividend is under an obligation (pursuant to a short sale or otherwise) to make related payments with respect to positions in SSRP:

“Because we find that the Swiss Equities are SSRP for purposes of section 246 and the related regulations, SIHP is barred from claiming FTC under section 901(a) and (k)(1). We hold that SIHP has not satisfied the statutory requirements to claim the FTC.”

Thus, the Tax Court sustained the IRS’s adjustments in their entirety, entering a decision for the respondent.

Professional Takeaways for Tax Practitioners

For CPAs, EAs, and corporate tax directors, the SIH Partners decision provides several critical practice insights:

Mechanical Safe Harbors are Not Invulnerable: Literal compliance with a quantitative test (such as the 70% threshold in the Substantial Overlap Test) will not protect a transaction from recharacterization if a subjective anti-abuse rule is present. Practitioners must evaluate transactions under both the literal text of the safe harbor and the broad intent of the accompanying anti-abuse provisions.
The Critical Importance of Pre-Transaction Profit Analyses: If a taxpayer claims to have a non-tax business purpose or an expectation of pre-tax profit, that expectation must be documented before entering into the transaction. The analysis must be robust, realistic, and account for all transaction costs (such as foreign currency fees and slippage) and realistic tax-withholding recovery timelines. Thin, incomplete, or over-optimistic spreadsheets prepared after the fact will be dismantled by the IRS’s experts at trial.
Subjective Valuations Will Be Closely Scrutinized: Attempting to inflate “pre-tax profit” by attributing massive, subjective economic benefits to a pre-existing firm hedge (such as the $121 million benefit claimed by the taxpayer’s expert) will find little favor with the Tax Court. The economic realities of the specific transaction must stand on their own.
Coordinating Code Sections: Practitioners must remain aware of how definitions and holdings under one section (such as SSRP under I.R.C. § 246) automatically cascade into other vital provisions (such as the foreign tax credit limitations of I.R.C. § 901(k)).

Prepared with assistance from Gemini Notebook.