Bsi Holdings, LLC v. Ariz. Dep't of Transp., 417 P.3d 782

BSI Holdings, an Oregon LLC owning a private jet used by Arizona resident Richard Burke, had a tie-down/hangar arrangement at Scottsdale Airport.
ADOT audited BSI and concluded the jet was "based in" Arizona more than 210 days per year (2004–2012), triggering a higher tax rate and a $161,004 assessment; BSI had paid the lower nonresident rate for those years.
BSI sued after administrative relief failed; both parties moved for summary judgment on the meaning of "day" in A.R.S. § 28-8336 (the statute taxing nonresident aircraft based in AZ more than 90 but less than 210 days).
The tax court ruled for BSI, interpreting "day" as a full 24-hour period and construing ambiguity in favor of the taxpayer; the court of appeals reversed, adopting ADOT’s view that any fraction of a day on the ground counts as a day.
The Arizona Supreme Court granted review to decide the meaning of "day," but concluded the term must be read in context with the undefined phrase "based in," which was not fully litigated below; the Court remanded for further fact-finding on what it means for an aircraft to be "based in" Arizona and how to count days accordingly.

Issue	Plaintiff's Argument	Defendant's Argument	Held
Meaning of "day" in A.R.S. § 28-8336	"Day" means a full 24-hour period (midnight-to-midnight)	Any fraction of a calendar day when the aircraft is on the ground in AZ counts as a day	Court rejected both extremes: momentary presence alone does not create a "based in" day, nor must a day be a full 24-hour block; meaning depends on "based in" context and requires further factfinding
Role of common law definition counting fractions of a day	N/A	ADOT: common law treats any fraction as a day (statutes of limitation context)	Court found common-law counting inapposite here because "based in" is not simply a consecutive-day counting problem
Deference to ADOT’s interpretation	N/A	ADOT urged deference to its administrative interpretation	Court declined deference because term is not technical, agency position was not a formal, established rule, and the statute lacks precise agency-crafted guidance
Remedy and next steps	BSI sought to retain lower tax rate and deny assessment	ADOT sought enforcement of higher assessment and lien	Case remanded to tax court to define "based in," apply it to the record, and then count days (construing any remaining ambiguity for taxpayer as a last resort)

State ex rel. Ariz. Dep’t of Revenue v. Capitol Castings, 207 Ariz. 445 (2004) (if statutory intent cannot be determined, construing tax statutes in favor of taxpayers)
Harris Corp. v. Ariz. Dep’t of Revenue, 233 Ariz. 377 (2013) (tax statutes are construed for taxpayers only after exhausting other tools of construction)
Maciborski v. Chase Serv. Corp. of Ariz., 161 Ariz. 557 (App. 1989) (common law treats any fraction of a day as a day in contexts like statutes of limitations)
DeWitt v. McFarland, 112 Ariz. 33 (1975) (domicile principles for tax purposes)
Burbey, 243 Ariz. 145 (2017) (statutory-construction framework: effectuate text first; use context and secondary tools when ambiguous)