1. The question, as people ask it
"How much are ADU permit fees in Phoenix?" — also asked as "What does Scottsdale charge to permit a casita?", "Do I pay impact fees on an ADU?", and "Why is the permit quote so different from one city to the next?"
2. The short answer
There is no single ADU permit fee. Each city charges from its published schedule, and the two cities use different formulas.
- Phoenix prices the building permit from the project valuation on a sliding table, adds a plan-review fee of 80% or 100% of the permit fee, and charges development impact fees by impact fee area. Much of the older city is in the "Balance of City" area, where most impact-fee categories are $0.
- Scottsdale prices the building permit by square footage plus a base fee, prices plan review by square footage, charges a flat application fee for ADU staff review, and collects water and wastewater development fees by meter size.
Below are the published numbers. Your total depends on your valuation, floor area, meter, and location.
3. Phoenix (fee schedule effective January 20, 2026; impact fees effective June 23, 2025)
Building permit, Table A (valuation-based). From the Planning & Development Department fee schedule, Appendix A.2:
- $1 – $1,000 — : $195 base fee
- $1,001 – $10,000 — : $195 on the first $1,000, plus $12 per additional $1,000
- $10,001 – $50,000 — : $303 on the first $10,000, plus $10 per additional $1,000
- $50,001 – $200,000 — : $703 on the first $50,000, plus $9 per additional $1,000
- $200,001 – $1,000,000 — : $2,053 on the first $200,000, plus $9 per additional $1,000
The schedule's own example: a $250,500 project pays "$2,053 base fee plus $459 (51 × $9) … Total permit fee cost of $2,512." Valuation "is based on the higher of the project valuation as calculated by Planning & Development or the project valuation as provided by the applicant."
Plan review. "Residential with project valuations of $50K or less … 100% of the permit fee, minimum $195"; "Residential with project valuations of over $50K … 80% of the permit fee, minimum $195." Standard plans: 80% of the permit fee for the base plan. Single-family design review: $195 per hour, minimum $98. Residential addition plot-plan review: $195 per hour, minimum $98. Each additional utility meter per utility: $98.
Impact fees (single-family dwelling, meter up to 1 inch). Phoenix charges by impact fee area. Selected areas from the 2025 schedule:
- Fire — Northeast: $1,282; Laveen West (on-project): $1,165; Ahwatukee (off-project): $1,625; Balance of City: $1,833; : $0
- Police — Northeast: $348; Laveen West (on-project): $348; Ahwatukee (off-project): $348; Balance of City: $348; : $0
- Parks — Northeast: $1,409; Laveen West (on-project): $1,474; Ahwatukee (off-project): $2,082; Balance of City: $1,094; : $0
- Libraries — Northeast: $216; Laveen West (on-project): $133; Ahwatukee (off-project): $205; Balance of City: $0; : $0
- Major arterials — Northeast: $2,330; Laveen West (on-project): $2,330; Ahwatukee (off-project): $0; Balance of City: $0; : $0
- Storm drainage — Northeast: $0; Laveen West (on-project): $0; Ahwatukee (off-project): $1,401; Balance of City: $0; : $0
- Wastewater collection — Northeast: $5,127; Laveen West (on-project): $5,127; Ahwatukee (off-project): $0; Balance of City: $0; : $0
- Wastewater treatment — Northeast: $3,753; Laveen West (on-project): $3,753; Ahwatukee (off-project): $1,071; Balance of City: $1,071; : $1,071
- Water transmission — Northeast: $14,046; Laveen West (on-project): $14,046; Ahwatukee (off-project): $1,703; Balance of City: $1,703; : $0
- Water treatment — Northeast: $4,387; Laveen West (on-project): $4,387; Ahwatukee (off-project): $4,387; Balance of City: $4,387; : $4,387
- Water resource acquisition — Northeast: $2,009; Laveen West (on-project): $2,009; Ahwatukee (off-project): $0; Balance of City: $2,009; : $2,009
The city's estimate page adds: "The Administrative Charge is 1% of the Gross Impact Fee, and is non-refundable," and the net fee "may be reduced on permits that are eligible to receive impact fee credit." The schedule lists "Single Family" and "Multifamily" dwellings; it does not name accessory dwelling units, so whether an ADU is assessed as a dwelling, and in which category, is a question for the Growth and Infrastructure staff before you budget.
4. Scottsdale (fee schedules effective July 1, 2026; development fees effective September 15, 2025)
Application. Development Review – Staff Approval, "Accessory Dwelling Units (ADUs): $131." Pre-application: $131.
Building permit, Single Family Detached Structure (Permit Fee Schedule – Residential):
- Base fee — : $237
- Livable area with A/C — : $0.94 per sq. ft.
- Covered area, non-A/C — : $0.54 per sq. ft.
- Certificate of Occupancy — : $195
- GIS fee — : $379
- Lowest floor certificate review — : $363
A single-family addition uses the same base fee and per-square-foot rates. Fence walls: $237 base plus $0.27 per linear foot.
Plan review (Plan Review Fee Schedule – Residential): custom homes and additions, "$0.54 sq. ft." of livable area and "$0.34 sq. ft." of covered non-A/C area; fences and retaining walls $0.18 per linear foot; miscellaneous reviews $121 per hour. The schedule notes it "is not all-inclusive and other fees may apply."
Water and wastewater development fees (Schedule #09-15-25), paid "before issuance of a building permit":
- 5/8, 3/4 and 1 inch — Wastewater: $8,836; Total: $6,028; : $14,864
- 1½ inch — Wastewater: $44,180; Total: $30,140; : $74,320
Scottsdale's ADU rules require separately metered utilities, so whether a new ADU meter triggers a new development fee is the first question to ask the One Stop Shop.
5. A worked comparison, using the schedules only
Take a 600-square-foot detached ADU with 100 square feet of covered patio and a builder valuation of $180,000.
- Phoenix permit: $703 on the first $50,000, plus 130 × $9 = $1,170, so $1,873. Plan review at 80%: $1,498. Design review and plot-plan review at the minimums: $196. Subtotal before impact fees: about $3,567. Impact fees: $0 in most categories in the Balance of City area, plus the water and wastewater treatment and water-resource charges listed above if assessed.
- Scottsdale permit: $237 base + 600 × $0.94 ($564) + 100 × $0.54 ($54) + $195 certificate + $379 GIS = $1,429. Plan review: 600 × $0.54 ($324) + 100 × $0.34 ($34) = $358. ADU application $131. Subtotal: about $1,918, plus $14,864 if a new 1-inch meter is assessed.
These are arithmetic on published rates, not quotes. Neither city's schedule is all-inclusive.
6. What's still unsettled
- Whether an ADU pays impact or development fees at all, and in which category. Neither city's schedule names ADUs. Both answers require a staff determination.
- Phoenix impact fee area. The area boundaries are on the city's map; a parcel-level check decides which column applies.
- Other cities. Goodyear, Buckeye, Surprise, Peoria, Glendale, Avondale, Litchfield Park, unincorporated Maricopa County, Tempe, Mesa, Gilbert, and Chandler each publish their own schedules. This page does not cover them.
- Schedules change on fiscal-year cycles. Phoenix's current schedule took effect January 20, 2026; Scottsdale's July 1, 2026. Re-check before relying on a number.
