CFC Rules: When a Foreign Subsidiary Triggers US Tax

A foreign corporation becomes a CFC when US shareholders, each owning at least a tenth of it by vote or value, collectively own more than half of it. Ownership counts shares held directly, through other entities, and in some cases through family members, so it's easy to cross the threshold without a single person owning a majority themselves. If you're forming a foreign subsidiary that's wholly owned by your US parent, it's almost always a CFC from day one; the harder cases are joint ventures and minority-stake foreign investments where you need to actually run the ownership math rather than assume.

Before the current international tax regime, US shareholders mostly deferred tax on a foreign subsidiary's active business income until it was distributed. That deferral is largely gone for CFCs today. Under the GILTI rules, a US shareholder generally includes a share of the CFC's tested income each year, computed after subtracting a routine return on the CFC's tangible depreciable assets, whether or not any cash actually comes home. Say your foreign subsidiary earns solid profit and reinvests every dollar into local growth: you can still owe US tax on a slice of that profit the same year, which is a cash flow surprise if nobody modeled it in advance.

Separately from GILTI, certain categories of a CFC's income, mainly passive income like dividends, interest and royalties, and some related-party sales and services income, get included currently under the older Subpart F rules regardless of the GILTI calculation. These categories exist to stop US companies from parking passive income in a low-tax foreign entity indefinitely. If your foreign subsidiary is a genuine operating business selling to unrelated local customers, Subpart F usually matters less than GILTI; if it's holding investments or billing related entities, look at Subpart F first.

US shareholders of a CFC generally have to file an information return each year reporting the subsidiary's financials, ownership structure and the relevant income calculations, even in a year with no US tax actually due. Say you skip a required filing one year: the initial penalty for Form 5471 is $10,000 per form per year, with additional continuation penalties if you still haven't filed after the IRS notifies you, whether or not you owed any actual US tax on the subsidiary's income. This is one of the more expensive paperwork mistakes in international tax precisely because it's disconnected from your actual tax liability.

Taxes your CFC already pays to its local government usually generate a US foreign tax credit that offsets some or all of the GILTI or Subpart F inclusion, so the practical bill is often much smaller than the raw inclusion amount suggests, especially in a country with a meaningful corporate tax rate of its own. The credit calculation has its own limitations and category rules, so it's rarely as simple as netting the two tax bills against each other, but it's the reason GILTI planning conversations always start with where the subsidiary actually operates, not just how much it earns.

Before setting up a new foreign subsidiary, model the GILTI exposure using a realistic profit projection, not a break-even assumption, since the tax hits regardless of distributions. Check whether a check-the-box election to treat the foreign entity as disregarded, rather than as a separate CFC, changes your outcome; this is a real, commonly used planning tool, but the right answer depends heavily on your specific structure and the foreign country's own tax treatment, so confirm it with an international tax advisor rather than assuming it works the same way it did for a different company's structure.

Before you open the next foreign entity, work through these checks:

• Model GILTI exposure with a realistic profit projection rather than a break-even assumption, since the tax applies whether or not the subsidiary distributes cash.
• Count US shareholders and their ownership, including indirect and family holdings, to see whether the entity crosses the more-than-half CFC threshold.
• Estimate the local taxes the entity will pay, since these usually generate a foreign tax credit that can offset part of the inclusion.
• Add the annual Form 5471 filing to your compliance calendar, because penalties apply even in a year with no US tax due.
• Ask your advisor whether a check-the-box election to treat the entity as disregarded fits your structure.