A tax inversion is a corporate restructuring in which a U.S. company reincorporates in a foreign country, usually by merging with a smaller foreign business, so that the combined enterprise sits under a foreign parent and pays less overall tax. Operations, employees, and headquarters typically stay put in the United States. What changes is the legal address at the top of the ownership chart, and with it the rules that govern how the group’s worldwide profits are taxed.
How the Deal Is Structured
The usual pattern begins with a U.S. corporation identifying a smaller company based in a country with a lower corporate tax rate. Ireland, the United Kingdom, and the Netherlands have been common destinations. The two businesses merge, and the combined company is reorganized under a new parent registered in the foreign country. Shareholders of the original U.S. company exchange their domestic shares for stock in the new foreign parent.
Once the deal closes, the former U.S. corporation becomes a subsidiary of the foreign parent. Day-to-day work does not change. The same people show up at the same offices to make the same products. But legal ownership now runs through a foreign holding company, and that shift is what unlocks the tax planning.
Where the Tax Savings Actually Come From
Changing the legal address by itself saves relatively little. The real benefit comes from how money is routed between the parent and subsidiary after the merger closes.
Earnings Stripping Through Intercompany Debt
The most common technique has the foreign parent lending money to its U.S. subsidiary, or having the U.S. subsidiary issue debt to the parent as a dividend. The U.S. subsidiary then pays interest on that debt, and the interest is deductible against its U.S. taxable income. The interest income lands with the foreign parent or a low-tax affiliate, where it may be taxed at a fraction of the U.S. rate or not at all. The Treasury Department has described this as a key incentive for foreign-parented firms to “load up their U.S. subsidiaries with related-party debt.”
Territorial Versus Worldwide Taxation
Before the 2017 tax overhaul, the United States taxed corporations on worldwide income, with a credit for foreign taxes paid. Inverted companies could redomicile to a country with a territorial system, where the parent owed tax only on income earned inside its new home country. Profits from operations in third countries could accumulate overseas without triggering additional home-country tax.
The Section 7874 Thresholds
Section 7874 of the Internal Revenue Code is the main anti-inversion provision. It sorts transactions by what percentage of the new foreign parent’s stock ends up in the hands of the former U.S. shareholders, and the consequences step up sharply at two lines.
The 80 Percent Rule
If former shareholders of the U.S. company hold 80 percent or more of the new foreign parent’s stock, by vote or value, the IRS treats the foreign parent as a domestic corporation for all federal tax purposes. The reincorporation is ignored, and the company owes the same taxes it would have owed had it never left. The rule stops a U.S. company from merging with a tiny foreign shell and calling itself foreign when ownership has barely shifted.
The 60 Percent Rule
When former shareholders hold between 60 and 79.9 percent, the foreign incorporation is respected, but the company pays a steep price. Any “inversion gain” recognized during a 10-year window cannot be reduced by tax attributes that would normally lower the bill, such as net operating losses or credits. The 10-year applicable period starts when property is first transferred as part of the acquisition and runs through the 10th anniversary of the final transfer.
Corporate insiders take a personal hit as well. Section 4985 imposes an excise tax on officers, directors, and 10-percent shareholders on the value of specified stock compensation, including options, held at any point during the 12 months spanning six months before through six months after the inversion date. The rate is tied to the top capital gains rate under Section 1(h)(1)(D).
The Substantial Business Activities Exception
A company can sidestep both thresholds entirely if it has genuine business presence in the new home country. Treasury regulations require that at least 25 percent of the combined group’s employees, employee compensation, assets, and income are located in or derived from that country. All four prongs must be satisfied, and the calculation looks at the entire worldwide group. Clearing this bar is difficult for most U.S. companies that merge with a relatively small foreign target.
What the 2017 Tax Law Changed
The Tax Cuts and Jobs Act of 2017 reshaped the economics of inversion in two fundamental ways: it cut the corporate rate and adopted a modified territorial system for all U.S. corporations, whether they inverted or not.
The federal corporate rate dropped from 35 percent to 21 percent, bringing the combined U.S. federal-and-state rate roughly in line with the average among other developed countries. When the U.S. rate was 35 percent and Ireland’s was 12.5 percent, the math for inverting was compelling. At 21 percent, the savings shrink considerably relative to the legal costs, regulatory scrutiny, and reputational exposure.
The TCJA also introduced Section 245A, which gives domestic C corporations a 100 percent dividends-received deduction on the foreign-source portion of dividends from specified 10-percent-owned foreign corporations. A U.S. parent can now bring home foreign earnings without additional U.S. tax on them, subject to a one-year holding period and the loss of any foreign tax credit or deduction on dividends that benefit from the deduction. That was one of the central benefits companies used to chase through inversions.
Two backstop provisions guard against profit shifting regardless of whether a company inverts. The first is the inclusion now called net CFC tested income, formerly known as Global Intangible Low-Taxed Income (GILTI), under Section 951A. U.S. shareholders of controlled foreign corporations must include their share of the subsidiary’s tested income in gross income each year. For 2026, the Section 250 deduction on this income drops from 50 percent to 40 percent, raising the effective minimum tax rate on those foreign earnings, and the prior exemption for a 10 percent return on tangible business assets abroad has been eliminated.
The second is the Base Erosion and Anti-Abuse Tax (BEAT) under Section 59A. It targets large multinationals averaging at least $500 million in gross receipts over the prior three years that make deductible payments to foreign affiliates exceeding 3 percent of total deductible payments. For taxable years beginning in 2026, the BEAT rate is 10.5 percent of modified taxable income, with a one-percentage-point increase for certain taxpayers. BEAT directly attacks earnings stripping by ensuring that companies loading up on deductible intercompany payments still pay a minimum level of U.S. tax.
What It Costs Shareholders
The corporate side tends to dominate coverage of inversions, but individual shareholders take their own hit. When shareholders swap stock in a U.S. corporation for stock in the new foreign parent, the exchange is generally a taxable event. Built-in capital gain must be recognized at the time of the inversion, even for shareholders who hold onto the new shares. Research on past inversions has estimated that the personal capital gains taxes paid by shareholders offset roughly 39 percent of the corporate tax savings the deal generates. For shareholders with a low cost basis or a high capital gains rate, the personal tax bill from the exchange can exceed their share of the corporate benefit.
Insiders who orchestrated the deal face the Section 4985 excise tax on top of that. Between the shareholder-level capital gains, the insider excise tax, the Section 7874 penalties above 60 percent, and the anti-abuse rules in GILTI and BEAT, a modern inversion has to overcome layers of friction that did not exist when the strategy first became popular.