When is a foreign corporation excluded from a California water's edge combined report?
Edvin Givargis Published 7 minute read
The short answer
A corporation organized outside the United States is excluded from a water's edge combined report unless the average of its property, payroll, and sales factors within the United States is 20 percent or more. The exclusion is not absolute: even a foreign corporation below the threshold enters the combined report to the extent of its income effectively connected with a United States trade or business, determined under Internal Revenue Code principles but without regard to treaty protection, and a controlled foreign corporation enters in the ratio of its Subpart F income to its earnings and profits. A foreign corporation that is itself a California taxpayer, stays below the 20 percent threshold, and has no effectively connected income can therefore file on a water's edge basis with little or none of its income in the measure, leaving the minimum franchise tax as the practical liability.
Who is in a water's edge group
The water's edge election replaces worldwide combined reporting with a combined report limited to the entities Revenue and Taxation Code Section 25110 describes. The categories that decide most files: corporations incorporated in the United States, wherever they operate, are included (Section 25110(a)(1)(C)); and any corporation other than a bank, regardless of the place where it is incorporated, is included if the average of its property, payroll, and sales factors within the United States is 20 percent or more (Section 25110(a)(1)(B)). The statute reaches domestic international sales corporations and export trade corporations as well, but the 20 percent test is where a foreign operating company's inclusion is usually decided.
Two partial inclusion rules then qualify the exclusion. A foreign corporation below the threshold is nonetheless included to the extent of its income derived from or attributable to sources within the United States and its factors assignable to a location within the United States (Section 25110(a)(2)(A)(i)), which the regulations measure by effectively connected income concepts. And a controlled foreign corporation with Subpart F income is included to the extent determined by multiplying its income and factors by the ratio of its Subpart F income to its current earnings and profits (Section 25110(a)(2)(A)(ii)). Exclusion from the group is therefore never the end of the analysis; it is the frame within which the two overlays are tested.
The 20 percent test
The test averages three factors, property, payroll, and sales, computed on a United States basis against the corporation's worldwide denominators. Although California apportions income under a single sales factor, the three-factor average continues to govern this inclusion test; the Franchise Tax Board reached that conclusion when the apportionment formula first moved away from equal weighting, and the statute's text has not changed (Legal Ruling 95-5). Two computational rules decide close cases. First, a factor the corporation does not have on a worldwide basis is disregarded, and the average is taken over the factors that remain (Cal. Code Regs. tit. 18, § 25110(d)(2)). A corporation with no property or payroll anywhere is measured on its sales factor alone, while a corporation with worldwide property and payroll but none in the United States averages two zeros against its United States sales percentage. The arithmetic rewards real operations outside the United States: significant United States sales divided across three factors can still produce an average below 20 percent. Second, sales between the foreign corporation and members of the water's edge group are eliminated from both the numerator and the denominator, which can move the percentage in either direction and should be computed, not assumed.
The effectively connected income overlay
The partial inclusion rule for United States source income is measured by effectively connected income, with two modifications that matter. Effective connection is determined under the Internal Revenue Code, but provisions of United States income tax treaties that would limit the application of the effectively connected income rules are not followed (CCR § 25110(d)(2)(F)1.a). A foreign corporation that relies on a permanent establishment article to escape federal net-basis taxation cannot rely on it for California; the question is whether the income is effectively connected under the Code alone. In addition, certain foreign source income that the Code deems effectively connected is included as well (CCR § 25110(d)(2)(F), incorporating IRC Section 864(c)(4)(B)). The operative sequence for a foreign service provider is therefore federal in form but broader in result: identify whether the corporation is engaged in a United States trade or business, classify its income under the Section 864 rules, and disregard the treaty. Income that is not effectively connected under that analysis, for example fees for services performed entirely outside the United States, does not enter the combined report of an excluded foreign corporation, whatever California's own sourcing rules would say about the same receipts.
Why the answer can be the minimum tax
The mismatch between the inclusion rules and California's sourcing rules is the planning engine, and it runs in both directions. California sources receipts from services to the location of the customer's benefit, and receipts from asset management services to the domicile of the investors, under the market-based sourcing regulations (CCR § 25136-2, as amended effective for taxable years beginning on or after January 1, 2026, and CCR § 25137-14 for mutual fund service providers). Those receipts can make a foreign corporation a California taxpayer under the doing business thresholds of Revenue and Taxation Code Section 23101(b) even with no United States presence. But once that corporation elects water's edge, the measure of its tax is built from the combined report Section 25110 describes, and its own income enters that report only through the 20 percent test and the partial inclusion overlays. A foreign corporation below the factor threshold, with no effectively connected income and no Subpart F inclusion, files Form 100W with a measured tax at or near zero, and pays the minimum franchise tax. The corporation is a taxpayer, the return is due, and the election must be valid; what changes is the measure.
Election mechanics
The election is made on an original, timely filed return for the year of election, computed consistently with a water's edge election and accompanied by the prescribed notification (Revenue and Taxation Code Section 25113(a)). Every taxpayer member of the self-assessed group must elect. The commitment is real: the election remains in effect until terminated, may not be terminated without Franchise Tax Board consent until it has been in effect for at least 84 months, and after termination another election is barred for taxable years beginning within the following 84 months (Section 25113(c)). A foreign affiliate that later becomes a California taxpayer in its own right does not silently break the group's election; the current rules provide a deemed election in defined circumstances, but the conditions are specific and the affiliate's filing posture should be confirmed rather than assumed.
Practice notes
The file that substantiates the position has three parts. First, the factor computation: the 20 percent test is computed entity by entity and year by year, and United States payroll or property added for commercial reasons can move a corporation across the threshold in a later year, so the computation belongs in the annual workpapers rather than in the planning memo alone. Second, the effectively connected income analysis: the conclusion that the corporation has no United States trade or business should be documented under the Code rules on their own terms, because the treaty that protects the federal position does not protect the California one. Third, the election itself: the validity, scope, and age of the election decide every downstream answer, and the 84-month commitment means the structure must make sense across the full election period, not only in the year it is designed.
This article states the law as of September 11, 2026
Statutes, rates, thresholds, and agency practice change, and a different set of facts can change the answer. Before acting on anything discussed above, contact G&G State Tax Group to confirm what has changed since this was written and how the rules apply to a specific situation.
G&G State Tax Group, LLC is a state and local tax advisory firm. The firm provides state and local tax consulting and representation in state and local tax controversies. G&G does not prepare or file tax returns, perform attest services, or provide bookkeeping, and is not a CPA firm.