Clause. This argument rests on two premises: first, that appellant's Illinois operations were responsible for some of the profits generated by sales in Iowa; and, second, that a formula that reaches any income not in fact earned within the borders of the taxing State violates due process. The first premise is speculative and the second is foreclosed by prior decisions of this Court.

Appellant does not suggest that it has shown that a significant portion of the income attributed to Iowa in fact was generated by its Illinois operations; the record does not contain any separate accounting analysis showing what portion of appellant's profits was attributable to sales, to manufacturing, or to any other phase of the company's operations. But appellant contends that we should proceed on the assumption that at least some portion of the income from Iowa sales was generated by Illinois activities.

Whatever merit such an assumption might have from the standpoint of economic theory or legislative policy, it cannot support a claim in this litigation that Iowa in fact taxed profits not attributable to activities within the State during the years 1968 through 1972. For all this record reveals, appellant's manufacturing operations in Illinois were only marginally profitable during those years and the high-volume sales to Iowa customers from Iowa warehouses were responsible for the lion's share of the income generated by those sales. Indeed, a separate accounting analysis might have revealed that losses in Illinois operations prevented appellant from earning more income from exploitation of a highly favorable Iowa market. Yet even were we to assume that the Illinois activities made some contribution to the profitability of the Iowa sales, appellant's claim that the Constitution invalidates an apportionment formula whenever it may result in taxation of some income that did not have its source in the taxing State is incorrect.

The Due Process Clause places two restrictions on a State's power to tax income generated by the activities of an interstate

business. First, no tax may be imposed unless there is some minimal connection between those activities and the taxing State. National Bellas Hess, Inc. v. Department of Revenue, 386 U. S. 753, 756. This requirement was plainly satisfied here. Second, the income attributed to the State for tax purposes must be rationally related to "values connected with the taxing State." Norfolk & Western R. Co. v. State Tax Comm'n, 390 U. S. 317, 325.

Since 1934 Iowa has used the formula method of computing taxable income. This method, unlike separate accounting, does not purport to identify the precise geographical source of a corporation's profits; rather, it is employed as a rough approximation of a corporation's income that is reasonably related to the activities conducted within the taxing State. The single-factor formula used by Iowa, therefore, generally will not produce a figure that represents the actual profits earned within the State. But the same is true of the Illinois three-factor formula. Both will occasionally over-reflect or under-reflect income attributable to the taxing State. Yet despite this imprecision, the Court has refused to impose strict constitutional restraints on a State's selection of a particular formula."

Thus, we have repeatedly held that a single-factor formula is presumptively valid. In Underwood Typewriter Co. v. Chamberlain, 254 U. S. 113, for example, the taxpayer challenged Connecticut's use of such a formula to apportion its net income. Underwood's manufacturing operations were conducted entirely within Connecticut. Its main office, however, was in New York City and it had branch offices in many States where its typewriters were sold and repaired. Applying a single-factor property formula, Connecticut taxed 47% of the company's net income. Claiming that 97% of its profits were

See, e. g., Underwood Typewriter Co. v. Chamberlain, 254 U. S. 113; Bass, Ratcliff & Gretton, Ltd. v. State Tax Comm'n, 266 U. S. 271; Ford Motor Co. v. Beauchamp, 308 U. S. 331.

generated by transactions in tangible personal property outside Connecticut, Underwood contended that the formula taxed "income arising from business conducted beyond the boundaries of the State" in violation of the Due Process Clause. Id., at 120.

Rejecting this claim, the Court noted that Connecticut "adopted a method of apportionment which, for all that appears in this record, reached, and was meant to reach, only the profits earned within the State," id., at 121, and held that the taxpayer had failed to carry its burden of proving that "the method of apportionment adopted by the State was inherently arbitrary, or that its application to this corporation produced an unreasonable result." Ibid. (footnote omitted).'

In individual cases, it is true, the Court has found that the application of a single-factor formula to a particular taxpayer violated due process. See Hans Rees' Sons, Inc. v. North Carolina ex rel. Maxwell, 283 U. S. 123; Norfolk & Western R. Co. v. State Tax Comm'n, supra. In Hans Rees', for example, the Court concluded that proof that the formula produced a tax on 83% of the taxpayer's income when only 17% of that income actually had its source in the State would suffice to invalidate the assessement under the Due Process Clause. But in neither Hans Rees' nor Norfolk & Western did the Court depart from the basic principles that the States have wide latitude in the selection of apportionment formulas and that a formula-produced assessment will only be disturbed when the taxpayer has proved by "clear and cogent evidence" that the income attributed to the State is in fact "out of all appropriate proportions to the business transacted . . . in that State," 283 U. S., at 135, or has "led to a grossly distorted result," 390 U. S., at 326.

General Motors Corp. v. District of Columbia, 380 U. S. 553,

See also Bass, Ratcliff & Gretton, Ltd. v. State Tax Comm'n, supra; Norfolk & Western R. Co. v. North Carolina ex rel. Maxwell, 297 U. S.

682.

on which appellant relies, does not suggest a contrary result. In that case the Court held that a regulation prescribing a single-factor sales formula was not authorized by the District of Columbia Code. It concluded that the formula violated the statutory requirement that the net income of a corporation doing business both inside and outside the District must be deemed to arise from "sources" both inside and outside the District. But that statutory requirement has no counterpart in the Constitution, and the Court in General Motors made clear that it did "not mean to take any position on the constitutionality of a state income tax based on the sales factor alone." Id., at 561.

The Iowa statute afforded appellant an opportunity to demonstrate that the single-factor formula produced an arbitrary result in its case. But this record contains no such showing and therefore the Director's assessment is not subject to challenge under the Due Process Clause."

8 The Court, it is true, expressed doubts about the wisdom of the economic assumptions underlying the challenged formula and noted that its use in the context of the more prevalent three-factor formula would not advance the policies underlying the Commerce Clause. But these considerations were deemed relevant to the question of legislative intent, not constitutional interpretation.

In his concurring opinion, Justice McCormick of the Iowa Supreme Court made this point:

"In the present case, Moorman did not attempt to prove the amount of its actual net income from Iowa activities in the years involved. Therefore no basis was presented for comparison of the corporation's Iowa income and the income apportioned to Iowa under the formula. In this era of sophisticated accounting techniques, it should not be impossible for a unitary corporation to prove its actual income from activities in a particular state. However, Moorman showed only that its tax liability would be substantially less if Iowa employed a three-factor apportionment formula. We have no basis to assume that the three-factor formula produced a result equivalent to the corporation's actual income from Iowa activities. Having failed to establish a basis for comparison of its actual income in Iowa with the income apportioned to Iowa under the single-factor formula, Moorman did not demonstrate that the single-factor formula

Appellant also contends that during the relevant years Iowa and Illinois imposed a tax on a portion of the income derived from the Iowa sales that was also taxed by the other State in violation of the Commerce Clause.10 Since most States use the three-factor formula that Illinois adopted in 1970, appellant argues that Iowa's longstanding single-factor formula must be held responsible for the alleged duplication and declared unconstitutional. We cannot agree.

In the first place, this record does not establish the essential factual predicate for a claim of duplicative taxation. Appellant's net income during the years in question was approximately $9 million. Since appellant did not prove the portion derived from sales to Iowa customers, rather than sales to customers in other States, we do not know whether Illinois and Iowa together imposed a tax on more than 100% of the relevant net income. The income figure that appellant contends was subject to duplicative taxation was computed by comparing gross sales in Iowa to total gross sales. As already noted, however, this figure does not represent actual profits earned from Iowa sales. Obviously, all sales are not equally profitable. Sales in Iowa, although only 20% of gross sales, may have yielded a much higher percentage of appellant's profits. Thus, profits from Iowa sales may well have exceeded the $2.5 million figure that appellant contends was taxed by the two States. If so, there was no duplicative taxation of the net income generated by Iowa sales. In any event, on this record its existence is speculative."

produced a grossly unfair result. Thus it did not prove unconstitutionality of the formula as applied." 254 N. W. 2d, at 757.

10 Since Illinois did not adopt its income tax until 1970, there was no possibility of any overlap until that year. The alleged overlap in the three years following Illinois' enactment of an income tax was 34.38% in 1970, 34.51% in 1971, and 37.01% in 1972.

11 Since there is no evidence in the record regarding the percentages of its total net income taxed in the other States in which it did business during