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Arizona Auto Insurance & Crash Law · Citizen Guide 06
Stacking & Multiple Insurance Policies
Arizona UM/UIM law can permit more than one policy or coverage to respond to the same loss. But stacking is not resolved by simply counting vehicles or policies. The controlling questions are which coverages actually apply, who purchased them, and whether the insurer validly used A.R.S. §20-259.01(H) to restrict the insured to one selected coverage.
Arizona allows stacking to be limited—but only through the statutory method
A.R.S. §20-259.01(H) governs multiple applicable UM/UIM policies and coverages purchased on different vehicles.
If multiple policies or coverages purchased by one insured on different vehicles apply to an accident or claim, the insurer may limit the insured to one policy or coverage selected by the insured.
Arizona recognizes both intra-policy and inter-policy stacking
One policy · multiple vehicles
Multiple UM/UIM coverages associated with different vehicles insured under a single policy.
Franklin squarely establishes that a single multi-vehicle policy can contain separate UIM coverages for purposes of subsection (H).
Multiple policies · multiple vehicles
Separate automobile policies provide UM/UIM protection associated with separate vehicles.
Subsection (H) also governs circumstances in which multiple policies purchased by one insured apply to the same accident.
Franklin changed the multi-vehicle-policy analysis
In Franklin v. CSAA General Insurance Co., the Arizona Supreme Court answered a question that had generated substantial disagreement: does a single policy covering several vehicles provide one UIM coverage or separate UIM coverages associated with each vehicle?
Coverage A
UIM purchased in connection with the first insured vehicle.
Coverage B
A separate UIM coverage for subsection (H) purposes even though it appears within the same policy.
Stacking question exists
The insurer must use subsection (H)'s prescribed method if it wants to restrict the insured to only one coverage.
The policy's generic limit-of-liability clause was not enough
CSAA's policy said its per-person UIM limit was the most it would pay regardless of the number of covered cars or premiums paid.
The Supreme Court nevertheless held that subsection (H) governs the insurer's effort to prevent stacking.
A valid Arizona anti-stacking limitation requires more than a limits clause
Franklin describes two distinct requirements for an insurer invoking §20-259.01(H).
Express and plain policy language
The policy must expressly and plainly limit stacking. The insured should be able to determine from the contract that the insurer is invoking the statutory restriction.
Selection-right notice
The insurer must satisfy subsection (H)'s requirement that the insured be informed of the right to select which one policy or coverage will apply.
The insured's right to select one policy or coverage is part of the statutory limitation
Section 20-259.01(H) contains two ways the selection-right notice can be supplied.
Inside the policy
The policy itself may contain a statement informing the insured of the insured's right to select one policy or coverage.
After notice of the accident
If the policy lacks the required statement, the insurer must provide written notice of the selection right within 30 days after receiving notice of the accident.
Why selection matters
Different policies or coverages may contain different limits, endorsements or claims consequences. Arizona therefore places the selection decision with the insured rather than the insurer.
Balzan answers the modern household-policy question
State Farm Mutual Automobile Insurance Co. v. Balzan, decided by the Arizona Supreme Court in 2026, addresses the meaning of “purchased by one insured.”
Named insured matters
Arizona's statutory offer-and-acceptance system gives the named insured the authority to accept or reject UM/UIM coverage.
Premium contribution is not enough
A resident relative or family member does not become a separate statutory purchaser merely because that person contributes money toward household expenses or premiums.
Community funds do not decide it
The fact that spouses paid premiums from community funds does not itself make each spouse an independent statutory purchaser.
Joint procurement can constitute one purchaser
When two named insureds act together to procure UM/UIM coverage, they can function collectively as the single statutory purchaser and constitute “one insured” under subsection (H).
After Balzan, ask who procured the coverage
The purchaser question should now be investigated from the insurance transaction itself.
Arizona stacking examples
| Coverage structure | Initial Arizona analysis |
|---|---|
| One policy · one vehicle | Ordinarily there is only one UM or one UIM coverage to apply. There is nothing additional to stack merely from that policy. |
| One policy · two vehicles | Franklin treats the multi-vehicle policy as providing separate UIM coverages for stacking purposes. Determine whether subsection (H) was validly invoked. |
| One policy · four vehicles | Potentially four UM/UIM coverages associated with four vehicles. A valid subsection (H) limitation may restrict the insured to one. |
| Three policies · one named insured · same insurer | Inter-policy stacking issue. Determine whether all policies apply and whether the insurer validly limited coverage under subsection (H). |
| Several policies · insurers within same managed group | Subsection (H) defines “insurer” to include insurers within a group under common management. |
| Child's policy + parents' jointly procured policies | Balzan demonstrates that the child's separately procured policy can constitute one coverage source while the parents' policies may be treated as a separate group purchased by one statutory purchaser. |
| Spouses jointly procure four policies | Under Balzan, the two named insureds can function collectively as “one insured” for subsection (H). |
| Family member merely helps pay premium | Premium contribution alone does not make that family member a separate statutory purchaser under Balzan. |
| Policies issued by unrelated insurers | Identify each applicable coverage and analyze each insurer's contractual and statutory rights separately. Do not assume one carrier's anti-stacking provision extinguishes another carrier's otherwise applicable policy. |
Franklin also rejects a separate argument based on the liability limit
Section 20-259.01(B) regulates how much UIM coverage an insured may purchase in relation to bodily-injury liability limits.
In Franklin, the Arizona Supreme Court held that subsection (B) does not independently prohibit an insured from ultimately receiving stacked UIM benefits exceeding the policy's bodily-injury liability limit.
Stacking increases available coverage—it does not create duplicate damages
Multiple insurance contracts do not convert a $200,000 compensatory loss into a $600,000 injury.
Example
| Item | Amount | Effect |
|---|---|---|
| Total bodily-injury damages | $400,000 | Legal measure of compensatory loss. |
| Liability recovery | $100,000 | Leaves $300,000 uncompensated. |
| UIM Coverage A | $100,000 | Potential source of gap protection. |
| UIM Coverage B | $100,000 | Potentially stackable if applicable and not validly limited. |
| UIM Coverage C | $100,000 | Potentially stackable if applicable and not validly limited. |
Arizona stacking workflow
Documents to obtain in an Arizona stacking claim
- every declarations page
- every complete auto policy
- UM/UIM endorsements
- vehicle schedules
- premium records
- policy applications
- named-insured information
- UM/UIM offer forms
- UM/UIM selection records
- renewal declarations
- anti-stacking clauses
- other-insurance provisions
- limit-of-liability provisions
- coverage denial letters
- reservation-of-rights letters
- post-accident selection notices
- proof of notice date
- claim opening date
- insured's policy selection
- household policy inventory
- proof of who procured each policy
- insurance applications
- communications with agent
- liability settlement information
- complete damages documentation
Common Arizona stacking mistakes
“One policy means one coverage.”
Not after Franklin. A multi-vehicle policy can contain separate UM/UIM coverages for stacking purposes.
“The policy says the limit never increases, so stacking is impossible.”
A generic limits clause does not replace compliance with §20-259.01(H).
“The insurer decides which policy applies.”
Arizona gives the selection right to the insured when a valid subsection (H) limitation applies.
“Everyone who paid premiums is a separate purchaser.”
Balzan rejects that approach. The inquiry focuses on who procured the UM/UIM coverage.
“Two spouses must always be two purchasers.”
No. Spouses who jointly procured coverage can function collectively as one statutory purchaser for subsection (H).
“Stacking means double damages.”
No. Multiple applicable coverages supply additional insurance for uncompensated damages; they do not automatically multiply the injury.
Arizona authority map
Frequently asked questions
Does Arizona allow UM/UIM stacking?
Potentially yes. Arizona permits multiple applicable UM/UIM coverages, but §20-259.01(H) allows an insurer to restrict multiple policies or coverages purchased by one insured on different vehicles to one selected policy or coverage if the statutory requirements are satisfied.
If one policy insures two cars, is there only one UIM coverage?
No. Franklin holds that a single policy insuring multiple vehicles provides separate UIM coverages for each vehicle for purposes of §20-259.01(H).
Can the insurer prohibit stacking?
Yes, but it must comply with §20-259.01(H). Franklin requires express and plain anti-stacking policy language together with compliance with the insured's statutory selection-right notice.
Who chooses which policy applies if stacking is validly limited?
The insured. Section 20-259.01(H) says the one applicable policy or coverage is selected by the insured.
What happens if the policy does not tell me I can select the coverage?
Subsection (H) requires the insurer to notify the insured in writing of the selection right within 30 days after the insurer receives notice of the accident. Franklin also requires an express and plain anti-stacking restriction in the policy itself.
Does paying part of the premium make me a separate purchaser?
Not by itself. Balzan holds that purchaser status turns on who exercised the legal authority to procure UM/UIM coverage, not simply who contributed funds toward the premium.
Are a husband and wife automatically separate purchasers?
No. Balzan holds that named insured spouses who act jointly to procure coverage can function collectively as one statutory purchaser under subsection (H).
What if an adult child has a separate policy?
A separately procured policy can constitute another coverage source. Balzan itself involved Connor's own policy in addition to the household policies procured by his parents.
Can an insurer rely only on language saying the limits do not increase because multiple cars are insured?
Not as a substitute for §20-259.01(H). Franklin requires the insurer to expressly and plainly limit stacking and satisfy the statutory selection-notice requirement.
Can stacked UIM exceed the policy's liability limit?
Potentially. Franklin holds that §20-259.01(B)'s limits on the amount of UIM purchased do not themselves prohibit total stacked UIM recovery exceeding the policy's bodily-injury liability limit.
Does stacking allow recovery above the actual damages?
Stacking concerns available insurance. It does not ordinarily create additional compensatory damages. The claim still requires proof of the actual uncompensated loss.
What is the first thing to do in a possible Arizona stacking case?
Find every applicable policy and every insured vehicle. Then identify each named insured, determine who procured each UM/UIM coverage, and obtain the complete anti-stacking and selection provisions.
Count the coverages before applying the limitation.
Identify every policy. Identify every insured vehicle. Determine which UM/UIM coverages actually apply. Identify the statutory purchaser under Balzan. Then read the anti-stacking clause and test it against §20-259.01(H) and Franklin. Only after those steps should the claim be reduced to one selected coverage.