Property tax on movable property follows the property, not its owner: a state may tax tangible personal property only when the property is physically present or habitually used inside its borders, and when an asset operates across several states, each state is limited to a fair share of the value based on how much the property actually uses that state. That rule replaced an older fiction that let an owner’s home state tax everything the owner owned no matter where it sat, and the modern framework built around it decides who can tax what, how much, and when.
Where Movable Property Is Taxable
The controlling rule comes from Union Refrigerator Transit Co. v. Kentucky, 199 U.S. 194 (1905). A Kentucky corporation kept its refrigerator cars permanently in other states, and Kentucky tried to tax the entire fleet. The Supreme Court struck the tax down, holding that taxation rests on reciprocity: the state that provides roads, protection, and public services gets to tax, and a state that provides nothing to a piece of property cannot tax it. Taxing property permanently outside the state, the Court said, was “rather of the nature of an extortion than a tax” and violated due process under the Fourteenth Amendment.1Justia. Union Refrigerator Transit Co. v. Kentucky, 199 U.S. 194 (1905)
Before that decision, courts used the doctrine of mobilia sequuntur personam, a convenience that treated all of an owner’s movable property as located at the owner’s domicile.2Justia. Buck v. Beach, 206 U.S. 392 (1907) Union Refrigerator ended that shortcut for tangible personal property. The right to tax follows where the property sits.
Property That Moves Through Several States
Physical presence is easy to identify when equipment stays put. It gets harder when trucks, railcars, aircraft, or barges are in one state on Monday and another on Thursday. Two questions then dominate: does the property have enough contact with a state to be taxed there at all, and if the owner wants to reduce a home-state assessment, what does the owner have to prove?
Habitual Employment Creates a Taxable Connection
In Braniff Airways v. Nebraska Board of Equalization, 347 U.S. 590 (1954), Braniff’s planes were registered elsewhere and only touched down in Nebraska for loading and unloading. Nebraska taxed an apportioned share of the fleet, and the Supreme Court upheld it. The test was “habitual employment” of the property in the state. Braniff’s regular scheduled stops, use of Nebraska airports, and roughly one-tenth of revenue drawn from Nebraska operations were enough contact to support an apportioned tax.3Legal Information Institute. Braniff Airways v. Nebraska Board of Equalization, 347 U.S. 590 (1954)
The point is that mobile assets do not need a permanent home in a state to be taxable there. Regular, purposeful use of the state’s infrastructure is enough.
The Owner Carries the Burden of Proving Situs Elsewhere
The flip side comes from Central Railroad Co. of Pennsylvania v. Pennsylvania, 370 U.S. 607 (1962). Central Railroad’s freight cars traveled in and out of Pennsylvania, and some spent part of the year in use by other railroads elsewhere. Pennsylvania taxed the full fleet at full value. The railroad argued that the portion absent during the tax year should be excluded, and the Court disagreed. A state may tax the full value of movable property unless the owner proves that a specific, identifiable portion has acquired a tax situs in another state, meaning another state could actually tax those units on an apportionment basis. Showing that cars were absent for part of the year was not enough.4Justia. Central R. Co. v. Pennsylvania, 370 U.S. 607 (1962)
This shifts the practical work onto the taxpayer. If you want your home state to back off part of an assessment, you need records identifying which units were where, and evidence that another jurisdiction has the power to tax those units. Vague claims about equipment traveling out of state will not carry the burden.
How States Divide the Value: Apportionment
Once mobile property can have taxable contact with more than one state, some method has to keep every state from taxing the full value. Apportionment does that work by dividing assessed value in proportion to the property’s actual use in each state.
The Mileage Ratio
The template came in Pullman’s Palace Car Co. v. Pennsylvania, 141 U.S. 18 (1891). Pullman ran sleeping cars nationwide, and Pennsylvania taxed a portion of its capital stock based on the ratio of miles operated inside the state to miles operated everywhere. The Court upheld the formula as a reasonable approximation of local presence.5Legal Information Institute. Pullman’s Palace Car Co. v. Pennsylvania, 141 U.S. 18 (1891) If a company runs 10,000 route-miles nationally and 1,500 of them lie in a given state, that state can tax 15% of the fleet’s value. Modern formulas commonly use in-state mileage over total mileage, or in-state days over total days in the year.
The Court extended the same approach to inland waterways in Ott v. Mississippi Valley Barge Line Co., 336 U.S. 169 (1949), rejecting an older “home port” rule for barges and letting Louisiana apportion by miles operated in the state.6Justia. Ott v. Mississippi Valley Barge Line Co., 336 U.S. 169 (1949) There is no separate rule for water, rail, or road.
Your Home State Cannot Ignore the Split
Apportionment only works if the domiciliary state respects it. Standard Oil Co. v. Peck, 342 U.S. 382 (1952), held that Ohio could not tax the full value of Standard Oil’s river boats and barges when those vessels operated almost entirely outside Ohio and were subject to apportioned tax in other states. The Court’s rule: “the rule which permits taxation by two or more states on an apportionment basis precludes taxation of all of the property by the state of the domicile.”7Justia. Standard Oil Co. v. Peck, 342 U.S. 382 (1952) If other states tax a share, the home state must reduce its assessment accordingly. The total tax across all jurisdictions should approximate what the owner would pay if the fleet sat in one place.
Formulas Have to Match Reality
An apportionment method also has to reflect what is actually happening. In Norfolk & Western Railway Co. v. Missouri State Tax Commission, 390 U.S. 317 (1968), the Supreme Court found Missouri’s assessment of the railroad’s rolling stock exceeded constitutional limits. The lesson is that a formula that produces an assessed value substantially higher than the property’s actual proportional presence in the state violates the Due Process and Commerce Clauses, however clean the math looks.8Legal Information Institute. Norfolk and Western Railway Co. v. Missouri State Tax Commission, 390 U.S. 317 (1968)
The Four-Part Test Any State Tax Must Pass
The modern framework for evaluating any state tax that touches interstate commerce, including property taxes on mobile assets, comes from Complete Auto Transit, Inc. v. Brady, 430 U.S. 274 (1977). A state tax is constitutional only when it satisfies all four prongs:9Justia. Complete Auto Transit, Inc. v. Brady, 430 U.S. 274 (1977)
- Substantial nexus. The property must have a meaningful connection to the taxing state, typically habitual physical presence or regular, purposeful use inside its borders.
- Fair apportionment. The tax must be proportional to the property’s actual presence or use in the state.
- No discrimination. The tax cannot treat interstate commerce less favorably than local commerce.
- Fair relationship to services. The tax must reasonably relate to what the state provides, such as roads, police protection, and fire services.
Failure on any one prong defeats the tax. The nexus prong ties back to due process, which the Constitution Annotated describes as requiring “some definite link, some minimum connection between a state and the person, property, or transaction it seeks to tax.”10Constitution Annotated. ArtI.S8.C3.7.11.4 Nexus Prong of Complete Auto Test for Taxes on Interstate Commerce
Goods Just Passing Through
Not every movable item that enters a state becomes taxable there. Goods merely in transit between states have not established the kind of connection that supports property tax, and taxing them would directly burden interstate commerce.
The line between “in transit” and “at rest” is where disputes cluster. Property that stops briefly for loading, unloading, or transshipment generally keeps its in-transit character. Goods stored for extended periods for business purposes beyond transportation can lose that protection. Many states have codified the point with statutory exemptions covering goods that remain in the state for fewer than a set number of days while bound for a destination elsewhere, with the owner typically bearing the burden of proving the goods were not consumed or permanently placed. When goods do come to rest, the ordinary situs rules take over: the property becomes taxable where it sits, and the owner’s home state loses its claim to that portion of value. Documentation showing the transit-oriented nature of each stop is what keeps this defense alive.
When Property Crosses International Borders
Property tax that touches foreign commerce meets a stricter standard. In Japan Line, Ltd. v. County of Los Angeles, 441 U.S. 434 (1979), Japanese shipping companies owned cargo containers already fully taxed in Japan that passed through California ports, where Los Angeles County imposed an ad valorem property tax. The Supreme Court struck the tax down. Property taxes on instrumentalities of foreign commerce must clear two requirements on top of the domestic Complete Auto Transit test: the tax must not create a substantial risk of international multiple taxation, and it must not prevent the federal government from “speaking with one voice when regulating commercial relations with foreign governments.” Both were violated because Japan already taxed the containers at full value and no federal authority sanctioned the additional tax.11Justia. Japan Line, Ltd. v. County of Los Angeles, 441 U.S. 434 (1979)
Shipping containers, aircraft on international routes, and equipment brought in temporarily for a project can all raise the Japan Line issue. A fairly apportioned domestic tax can still fail when it stacks on top of a foreign country’s full-value tax on the same property.
A separate constitutional provision, the Import-Export Clause of Article I, Section 10, forbids states from laying imposts or duties on imports or exports without congressional consent. The Supreme Court has read the clause narrowly for property taxes: a nondiscriminatory ad valorem property tax on goods no longer in import transit does not violate it. The clause targets taxes aimed at the act of importing or exporting, not general property taxes that happen to fall on goods with an international origin.12Legal Information Institute. Import-Export Clause
Software and Digital Assets
The whole framework above grew up around railcars, barges, trucks, and shipping containers. Applying it to software and digital assets is unsettled. The threshold question is whether software counts as “tangible personal property” at all, since the situs and apportionment rules assume the property is physical and movable.
State courts have split. Older decisions generally treated software as intangible, on the theory that the value lies in the code rather than the medium. More recent decisions trend toward treating prewritten, commercially available software as tangible personal property subject to property tax, particularly when it comes on physical media or lives on local hardware. Custom software written to a specific buyer’s specifications more often avoids that classification, though outcomes vary. Cloud-based software accessed remotely complicates matters further: if the servers are in one state and the users are in another, courts have not produced a unified answer on where the tax situs lies. Any business with significant software assets should expect the rules to vary substantially by state.
Who Pays on Leased Equipment
A frequent practical question is who owes property tax on leased movable equipment: the lessor holding title, or the lessee actually using it. The answer depends on the jurisdiction and sometimes on the nature of the lease. In many states the filing and payment obligation falls on the property owner by default. When a lease functions as a financing arrangement and the lessee is treated as effective owner for income tax purposes, some jurisdictions shift the property tax obligation to the lessee.
A company leasing a fleet of forklifts or copiers may assume the leasing company handles property taxes, only to find that local law treats the lessee as the responsible party. Lease agreements should say explicitly which party reports and pays personal property taxes. When the lease is silent, the default in most places falls on the titleholder, but exceptions are common enough that assumptions are risky.
Whoever pays, the situs rules are the same. Leased equipment is taxable where it is physically located and used, not where the lessor is headquartered. A leasing company based in one state with equipment deployed across a dozen others will see its fleet taxed in each of those states based on the equipment’s actual location on the assessment date.
Challenging the Assessed Value
Even when the right state is doing the taxing, the assessed value itself often draws a fight. Assessors typically use a cost approach: start with original acquisition cost and apply a depreciation schedule based on the property’s age and type. Heavy equipment tends to hold a higher percentage of original cost longer; general office equipment and computers depreciate faster.
The most common valuation dispute involves obsolescence. Standard depreciation schedules account for physical wear but often ignore functional and economic obsolescence. A five-year-old machine that still runs may have lost significant value because newer technology does the same job faster or cheaper, and economic conditions can make specialized equipment worth far less than its depreciated cost suggests. A taxpayer challenging an assessment usually needs an independent appraisal showing the assessed value exceeds fair market value after accounting for all forms of obsolescence.
The path for challenging an assessment follows a familiar sequence in most places: file a protest with the local assessor, attend an administrative hearing, appeal to a county or state equalization board if the assessor’s decision is unfavorable, and pursue judicial review as a last resort. Deadlines are tight and vary by location, often measured in weeks from the date of the assessment notice. Miss the initial protest deadline and you can forfeit the right to challenge the valuation for that tax year.