ADU Impact Fees: Phoenix vs Scottsdale
How do adu impact fees rules compare between Phoenix, AZ and Scottsdale, AZ?
Phoenix and Scottsdale have similar restriction levels.
Phoenix, AZ
Maricopa County
Phoenix charges modest development impact fees on ADUs under Arizona Revised Statutes Section 9-463.05. HB 2928 caps ADU impact fees in cities over 75,000 at 50 percent of single-family rates. Phoenix water and wastewater capacity charges apply where new meters are installed.
View full Phoenix rules →Scottsdale, AZ
Maricopa County
Scottsdale does not impose a dedicated ADU impact fee. Ariz. Rev. Stat. Sec. 9-461.18 limits the fees Scottsdale may charge on accessory dwelling units, preventing fees that would effectively prohibit ADU construction. Standard building permit and plan-review fees through Planning & Development Services apply, calculated on construction valuation. Water and sewer development fees may apply only when new utility connections are installed.
View full Scottsdale rules →Key Facts Comparison
| Fact | Phoenix | Scottsdale |
|---|---|---|
| Fee Authority | ARS §9-463.05 | - |
| ADU Cap | 50% of single-family rate | - |
| Typical Total | $4,000-$8,000 | - |
| Permit Fee | $500-$1,500 typical | - |
| Dedicated ADU Impact Fee | - | None in Scottsdale |
| State Cap | - | ARS 9-461.18 limits excessive ADU fees |
| Permit Fee Basis | - | Construction valuation |
| Utility Fees | - | Only if new connections required |
| Transportation Impact Fee | - | Not applied or reduced for ADUs |
| Reassessment | - | Maricopa County Assessor |
Highlighted rows indicate differences between cities.
Phoenix FAQ
How much are ADU impact fees in Phoenix?
Total impact fees typically run $4,000-$8,000 for a residential ADU. Under HB 2928, Phoenix must charge ADUs at no more than 50 percent of single-family rates in each category (water, wastewater, parks, fire, police, library, streets).
Are Phoenix ADUs under 750 sq ft exempt from impact fees?
No automatic exemption like California. Arizona HB 2928 caps ADU fees at 50 percent of single-family rates but does not provide a size-based exemption. Phoenix charges proportional fees regardless of ADU size.
Scottsdale FAQ
Does Scottsdale charge an ADU impact fee?
No. Scottsdale does not impose a dedicated ADU impact fee. You pay standard building, plumbing, mechanical, and electrical permit fees through Planning & Development Services based on construction valuation. Water and sewer development fees apply only if a new meter or service connection is installed.
Can Scottsdale impose excessive ADU fees?
No. Arizona Revised Statutes Sec. 9-461.18 limits the fees Scottsdale may impose on accessory dwelling units to prevent the state by-right mandate from being undermined. Fees must reasonably reflect the actual cost of services provided and cannot effectively prohibit ADU construction.
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