Background
Growmark, Inc., an agricultural cooperative, operates a fuel terminal in New Hampton, Iowa, where it stores propane in eleven 90,000-gallon tanks. The tanks rest on concrete saddles (piers) that function as foundations, but are held in place by gravity alone—they are not fastened or otherwise attached to the saddles. In 2023, the Chickasaw County assessor valued the eleven tanks at approximately $1,959,500 and included that amount in the taxable assessment of Growmark’s property. The Chickasaw County Board of Review affirmed, classifying the tanks as taxable “improvements” constructed or placed upon a foundation under Iowa Code § 427A.1(1)(c).
Growmark appealed to the Property Assessment Appeal Board (PAAB), which reversed, concluding that the tanks were unattached “equipment” under § 427A.1(1)(d) and therefore nontaxable personal property under § 427A.2. The PAAB relied heavily on McDermott Propane, LLC v. Board of Review, an unpublished 2022 court of appeals decision that had reached the same conclusion for 30,000-gallon propane tanks. The district court affirmed the PAAB, and the Iowa Supreme Court retained the case on appeal.
The Board of Review argued, among other things, that storage tanks have always been assessed as taxable improvements because they function as warehouses; that the court’s 2021 decision in StateLine Cooperative v. PAAB supported a storage-versus-processing test; and that decades-old Iowa Department of Revenue (DOR) materials—including appraisal manuals, valuation guides, and internal memoranda—required deference and confirmed that storage tanks are real property.
The Court’s Holding
The Iowa Supreme Court, in a unanimous opinion by Justice Oxley, affirmed the PAAB and the district court. The court held that Growmark’s propane tanks are unattached “equipment” under § 427A.1(1)(d), not “improvements” under § 427A.1(1)(c). Because equipment is taxable as real property only when attached to a building, structure, or improvement defined in paragraph (c)—and these tanks are concededly unattached—they fall outside the definition of taxable real property and constitute exempt personal property under § 427A.2. The court rejected the Board of Review’s storage-versus-processing test, explaining that the storage/processing distinction drawn in StateLine Cooperative addressed only whether items qualified as “machinery used in manufacturing” under paragraph (e) for manufacturing-tax-exemption purposes, and had no bearing on the separate improvement-versus-equipment question under paragraphs (c) and (d).
The court also declined to defer to the DOR’s internal manuals, valuation guides, and memoranda. Those materials—some dating to 1977 and 1985—were neither formal administrative rules promulgated through rulemaking nor contested-case decisions by the DOR itself. They did not address the specific threshold question of whether a tank is an improvement under paragraph (c) or equipment under paragraph (d), were inconsistent with current law (including the full manufacturing-equipment exemption effective since 2002), and were therefore unworthy of the deference required by Iowa Code § 17A.19(11)(c).
In a significant doctrinal development, the court used this case to overrule Iowa’s longstanding judicial rules that tax-imposing statutes are construed strictly against the taxing body and that tax exemptions are construed strictly against the taxpayer. The court found these principles are not grounded in the Iowa Code, may contradict each other and the general liberal-construction mandate of § 4.2, and rest on policy judgments properly left to the legislature. Going forward, Iowa courts will interpret tax statutes using the same ordinary-meaning principles applied to any other statute.
Key Takeaways
- Under Iowa Code § 427A.1(1), storage tanks resting on foundations but not physically fastened to them are “equipment,” not “improvements”; because equipment is taxable only when attached to a paragraph-(c) improvement, unattached tanks are exempt personal property.
- The storage-versus-processing distinction from StateLine Cooperative is confined to the manufacturing-machinery context of § 427A.1(1)(e) and does not determine whether an item is an improvement or equipment under paragraphs (c) and (d).
- DOR internal guidance documents (manuals, valuation guides, memos, bulletins) that are not formally promulgated administrative rules and do not address the specific statutory issue before the court are not entitled to § 17A.19(11)(c) deference.
- The Iowa Supreme Court overruled the prior rule that tax-imposition statutes are construed against the taxing body and tax-exemption statutes are construed against the taxpayer; Iowa courts will now apply ordinary statutory construction to tax provisions.
Why It Matters
The practical stakes are substantial. Thirty-one Iowa counties had already removed sub-30,000-gallon storage tanks from property assessments following the unpublished McDermott Propane decision; this published supreme court ruling extends the same principle to large commercial tanks and provides statewide, binding precedent. Agricultural cooperatives, fuel distributors, and industrial operators that store commodities in above-ground tanks held in place by gravity—rather than bolted or welded to their foundations—have a clear basis to exclude those assets from real property assessments.
The court’s abandonment of the pro-taxpayer and pro-taxing-authority construction canons is an equally significant jurisprudential shift. By committing Iowa courts to plain-meaning analysis without a thumb on the scale in either direction, the decision changes the interpretive landscape for future property tax disputes—and potentially for Iowa tax litigation broadly—requiring litigants to ground arguments in statutory text rather than relying on presumptions built into the old canons.