What is CFC Rules?

How it works

A CFC regime has three moving parts:

1. Control test. The threshold ownership above which a foreign company is "controlled" by domestic shareholders. Under the US Subpart F regime (per PwC US Corporate Group Taxation), a CFC is any foreign corporation where US shareholders own more than 50% of either voting power or value on any day of the corporation's tax year. EU member states under ATAD use a similar 50% threshold; some countries (Australia) require 50% control plus 5+ resident owners.
2. Shareholder definition. The US defines a "US shareholder" as any US person owning 10%+ of vote or value, directly, indirectly, or constructively (with attribution from family members and related entities). Constructive ownership rules are the trap: a US person owning nothing but related to a foreign owner can still be deemed a US shareholder. Under the OBBBA (July 2025), downward-attribution rules and pro-rata-share rules were modified — re-check structures formed before 2025.
3. Inclusion rules. Once a CFC is identified, certain income is taxed to the US shareholders whether or not it is distributed. The US has two parallel inclusion regimes:
   • Subpart F — passive and easily-shifted income.
   • GILTI / NCTI — under OBBBA, GILTI was renamed Net CFC Tested Income (NCTI) with a more favourable effective rate. The mechanism still sweeps most CFC operating profits beyond a routine return on tangible assets.

Other countries' CFC regimes (UK, France, Germany, EU ATAD) layer different mixes of:

• Tainted-income tests. Only passive / mobile income is re-attributed; active operating businesses are carved out.
• Effective tax rate tests. CFC rules trigger only if the foreign company's effective tax rate falls below a threshold (UK 75% of UK rate; EU ATAD 50% of EU member rate).
• Substance escape. EU ATAD allows a substance defence where the CFC carries on substantive economic activity supported by staff, equipment, assets and premises in its jurisdiction.

US shareholders and Form 5471

Every US shareholder of a CFC files Form 5471 annually as Category 4 or 5 — full schedules covering income, balance sheet, earnings & profits, transactions with related parties, and Subpart F / NCTI inclusions. Penalty for non-filing: $10,000/form/year + accumulating extensions. The form is the IRS's primary visibility tool into CFC structures.

Examples

• US founder owns 100% of a Cayman company. Cayman has 0% corporate tax. The Cayman company is a CFC. All operating income is NCTI-included on the founder's Form 1040 each year, even if not distributed. The Cayman 0% rate doesn't help; the US absorbs the gap. Form 5471 every year as Category 4/5. The structure is almost always tax-negative versus operating directly via a US LLC.
• French resident with a Singapore Pte Ltd, 100% owned. Singapore: territorial, ~17% headline corporate rate. France's CFC regime (article 209 B CGI) targets French residents controlling foreign entities in low-tax jurisdictions where the foreign tax is less than half what France would charge. Singapore's effective rate may or may not trip the threshold; needs a year-by-year analysis.

Common mistakes

• Assuming "low-tax = caught, otherwise safe". Most CFC regimes target structure regardless of actual tax savings — even profitable, fully-taxed CFCs can fall under the rules if the income type is tainted.
• Forgetting attribution. A US resident owning nothing in the foreign corporation can still be a "US shareholder" through constructive ownership rules.
• Skipping Form 5471 because "the company has no income". The form is required regardless. Missing it costs $10,000/year per CFC.
• Banking on substance defences. EU ATAD's substance escape requires real staff, real premises, real activity — not a token office and a director on retainer.