The Uniform Division of Income for Tax Purposes Act, known as UDITPA, is a model state law drafted in 1957 that gives states a common method for dividing a multistate corporation’s income among the jurisdictions that want to tax it. Roughly half of the states with a corporate income tax have adopted some version of it, and the Act also forms Article IV of the Multistate Tax Compact.1Multistate Tax Commission. Multistate Tax Compact The Act does one central thing: it sorts a company’s income into two buckets. Business income is divided across every state where the company operates using a formula. Non-business income is assigned to a single state based on what kind of income it is and where the underlying asset sits.
Who the Act Applies To
Section 2 covers any taxpayer earning income from business activity that is taxable both within and outside a state. Three groups are carved out: financial organizations, public utilities, and individuals performing purely personal services.2Multistate Tax Commission. UDITPA Issues to Consider for Revision Those industries have their own specialized apportionment rules.
A company falls under UDITPA when it is “taxable” in more than one state, meaning another state has jurisdiction to impose a net income tax on the business, whether or not it actually does so. The threshold question is nexus: does the company have enough of a connection to a state for that state to claim the right to tax it?
Two federal-law developments have reshaped how that nexus question plays out. Public Law 86-272 sets a floor: if a company’s only activity in a state is soliciting orders for tangible personal property, with those orders approved and shipped from outside the state, that state cannot impose a net income tax.3Multistate Tax Commission. Statement of Information Concerning Practices of Multistate Tax Commission and Signatory States Under Public Law 86-272 The Multistate Tax Commission’s 2021 revised statement takes the position that many common internet-based activities, including selling streaming content, providing post-sale customer support by chat, and using cookies for purposes beyond solicitation, can breach that protection.
The Supreme Court’s 2018 decision in South Dakota v. Wayfair, Inc. then overturned the physical-presence requirement for state tax jurisdiction.4Supreme Court of the United States. South Dakota v. Wayfair, Inc., 585 U.S. (2018) While the case involved sales tax, states have extended the economic nexus concept to corporate income taxes, asserting jurisdiction over businesses that cross revenue thresholds in the state without any office or employees there. A software company with no in-state footprint can now owe corporate income tax if its sales into that state are large enough. That change has made UDITPA’s apportionment rules relevant to far more companies than they used to be.
Business Income Versus Non-Business Income
This is the first and most consequential classification step. Everything downstream depends on it, because business income is divided by formula while non-business income is assigned to one state.
Section 1 defines business income as earnings from transactions and activities in the regular course of trade or business. It also includes income from property when acquiring, managing, and disposing of that property is an integral part of the company’s regular operations.2Multistate Tax Commission. UDITPA Issues to Consider for Revision Non-business income is everything else.
Tax administrators apply two tests. The transactional test asks whether the transaction itself is the kind of activity the business regularly performs to earn money. A manufacturer selling inventory produces business income because selling products is what the company does. The functional test looks at the asset instead. If the property that produced the income served an operational function in the business, the income is business income regardless of whether the specific transaction was routine.
Most disputes arise around the functional test. A company might sell a warehouse and treat the capital gain as non-business income, allocated to a single state, while the tax authority argues the warehouse was integral to operations and the gain should be apportioned across all states. Misclassifying a single large capital gain or dividend stream can shift millions of dollars in tax liability. Whether the two tests are independent alternatives or related parts of one inquiry has been a recurring source of litigation.
How Business Income Is Apportioned
Once income is classified as business income, Section 9 sends it through an apportionment formula. The original UDITPA formula uses three equally weighted factors: property, payroll, and sales. Each factor compares the company’s in-state presence to its total presence everywhere, producing a percentage. The three percentages are averaged into a single apportionment factor, which is then applied to total business income.
Property Factor
Sections 10 through 12 define the property factor as the average value of real and tangible personal property the company owns or rents and uses in the state, divided by the average value of all such property everywhere.1Multistate Tax Commission. Multistate Tax Compact Owned property is valued at original cost. Rented property is valued at eight times the net annual rental rate, which is rent paid minus any sublease income received.
Payroll Factor
Sections 13 and 14 measure compensation paid to employees whose services are performed in the state, divided by total compensation paid everywhere. Compensation covers wages, salaries, and commissions. The question is where the work happens, not where paychecks are mailed. When an employee works in multiple states, compensation is assigned to the state where the base of operations is located, or where the employee’s service is directed or controlled if there is no fixed base.
Sales Factor
Sections 15 through 17 compare the company’s in-state sales to its total sales everywhere. For tangible goods, sales are sourced to the state where the goods are delivered or shipped to the purchaser. For services and intangible income under the original UDITPA text, sales were sourced based on where the income-producing activity was performed, an approach commonly called cost of performance. That method has largely been replaced in practice.
How States Have Modified the Original Formula
UDITPA was written for a 1950s economy dominated by manufacturing. A reader trying to understand how the Act works today needs to know that most states no longer follow the original formula in two important ways.
The Shift to a Single Sales Factor
Most states with a corporate income tax have moved away from equally weighting property, payroll, and sales. The dominant trend is toward a single sales factor: the state ignores in-state property and payroll and apportions business income based solely on where the company’s sales land. The policy logic is that states want to attract corporate investment (factories, offices, employees) without penalizing companies through higher apportionment. A single sales factor rewards companies that put physical operations in the state while selling to customers elsewhere.
For a company with heavy in-state property and payroll but relatively low in-state sales, moving from a three-factor state to a single-sales-factor state can dramatically reduce its effective tax rate. The reverse also applies. A service company selling into a single-sales-factor state with no physical presence there faces a higher apportioned share than it would under the original formula.
Market-Based Sourcing for Services and Intangibles
The original UDITPA rule for sourcing non-tangible sales used cost of performance: receipts were assigned to the state where the company performed most of the work. In 2014, the Multistate Tax Commission recommended a major revision, replacing cost of performance with market-based sourcing.5Multistate Tax Commission. Review of MTC Model Sales/Receipts Sourcing and Special Industry Regulations Under market-based sourcing, receipts go to the state where the customer receives the benefit of the service.
The MTC adopted revised model regulations in 2017 to implement this approach. Over three-quarters of states with a corporate-level tax now use market-based sourcing.6Multistate Tax Commission. Section 1 and 17 Rules For a consulting firm headquartered in one state with clients scattered nationwide, that means sales factor numerators in every client’s state rather than a large concentration in the home state. Service businesses and software companies now face apportionment consequences wherever their customers sit.
Throwback Rule
Section 16(b) of UDITPA contains a provision designed to prevent “nowhere income,” meaning income that escapes taxation entirely because the destination state cannot tax the seller. If goods are shipped from the company’s state but the buyer sits in a state where the company lacks nexus, the throwback rule assigns those sales back to the state the goods shipped from.1Multistate Tax Commission. Multistate Tax Compact The same rule applies to sales to the federal government. Roughly half of the states that tax corporate income enforce a throwback rule. A handful use a variation called a throwout rule, which removes nowhere income from the denominator of the sales factor rather than adding it to the numerator.
How Non-Business Income Is Allocated
Non-business income is not apportioned by formula. Sections 4 through 8 assign it directly to one state based on the type of income and the location of the underlying asset.1Multistate Tax Commission. Multistate Tax Compact
- Rents and royalties from real property go to the state where the property is located.
- Rents and royalties from tangible personal property go to the state where the property is used by the renter or licensee.
- Capital gains from real property go to the state where the property sits.
- Capital gains from intangible property go to the taxpayer’s commercial domicile, meaning the principal place from which the business is directed or managed.
- Interest and dividends go to the commercial domicile.
- Patent and copyright royalties go to the state where the intellectual property is used. If the taxpayer’s commercial domicile is in a state where it is not otherwise taxable, those royalties may be pulled back to the domicile state rather than escaping taxation.
Commercial domicile does real work in this scheme. A holding company with passive investment income may find all of it allocated to the one state where executive management sits, rather than spread across multiple states by formula. That makes the domicile determination a high-stakes question for companies with large portfolios of intangible assets.
Alternative Apportionment Under Section 18
Section 18 is the safety valve. If the standard formula does not fairly represent the extent of a company’s business activity in a state, either the taxpayer or the tax administrator can request an alternative method. The available remedies include separate accounting (treating the in-state operation as a standalone entity), excluding one or more of the standard factors, adding an additional factor, or using any other equitable method that produces a fair result.
The party requesting the change bears the burden of showing that the standard formula is distortive. That is not an easy bar to clear. Courts and tax agencies treat the standard formula as presumptively correct, so merely showing that an alternative would produce a lower tax bill is not enough. The requesting party has to demonstrate that something about the business makes the formula genuinely unfair, such as massive in-state property holdings that generate almost no revenue there, or a business model the formula’s designers never contemplated. Section 18 cases are fact-intensive and heavily litigated.
What UDITPA Does Not Cover
UDITPA itself does not address what happens when a parent company and its subsidiaries operate as an integrated economic unit. That gap is filled by combined reporting requirements, which roughly half of the states now impose. Under combined reporting, a group of related corporations that function as a single unitary business must calculate taxable income as though they were one entity, then apportion a share to each taxing state based on the group’s combined factors. Without combined reporting, companies can shift income to subsidiaries in low-tax or no-tax states through intercompany transactions, such as paying royalties to a subsidiary that holds the group’s trademarks. Combined reporting collapses those transactions by treating the whole group as a single taxpayer, and the rules governing it live outside UDITPA.