ADU FeeMap

Updated Oct 18, 2026

A 750 sq ft ADU pays no impact fees anywhere in California. Here’s what the permits still cost in 15 cities and counties.

State law wipes out impact fees at 750 sq ft or less, but building permits, plan checks, school fees and utility charges remain. For a 1,000 sq ft unit, our itemized totals run from about $12,785 in Santa Cruz to as much as $51,548 in Mountain View, each built from the place’s official fee schedule.

15 jurisdictions · 14 cities, 1 unincorporated county · 50 official sources, each saved and quoted · checked Oct 18, 2026

Fees for a 1,000 sq ft backyard ADU, ranked

Modeled fees for a 1,000 sq ft detached ADU Solid: fees that apply. Hatched: fees that may apply (upper bounds, location- or project-dependent). Assumes a 2,000 sq ft main home (example) and today’s law.
  1. 01Mountain ViewSanta Clara County$8,997–$51,548
  2. 02Palo AltoSanta Clara County$24,613–$35,993
  3. 03WatsonvilleSanta Cruz County$26,391–$33,847
  4. 04Santa Cruz CountySanta Cruz County$19,702–$31,872
  5. 05San JoséSanta Clara County$14,045–$29,202
  6. 06Scotts ValleySanta Cruz County$17,183–$23,110+
  7. 07Santa CruzSanta Cruz County$12,785–$21,165
  8. 08CampbellSanta Clara County$9,824–$15,941+
  9. 09GilroySanta Clara County$9,959–$15,439+
  10. 10SunnyvaleSanta Clara County$2,353–$8,701+
  11. 11Los GatosSanta Clara County$2,068–$7,848+
  12. 12BerkeleyAlameda County$1,062–$6,442+
  13. 13CapitolaSanta Cruz County$545–$6,328+
  14. 14San FranciscoSan Francisco County$0–$5,380+
  15. 15OaklandAlameda County$5,170+

Compare all four sizes → · Itemize your own project →

State law

Three numbers decide most of the bill

  1. 750 sq ftAt or under this, no impact fees. Above it, they’re proportional to the main home.
  2. 500 sq ftSchool district fees start here.
  3. $5.38The 2026 statewide Level 1 cap on school fees, per sq ft.

From January 1, 2027, SB 1117 limits impact fees to the area over 750 sq ft. Read the rules, quoted from the statute →

News

Latest fee changes

State lawStatewide

SB 1117 signed: from 2027, ADU impact fees can only be charged on the area over 750 sq ft

The Governor approved SB 1117 (Chapter 809, Statutes of 2026) on September 29, 2026. It amends Gov. Code 66311.5: on lots with up to two ADUs, impact fees on an ADU over 750 sq ft must still be proportional to the primary home, and may only be charged on the area over 750 sq ft. Regular 2026 statutes take effect January 1, 2027. Until then, fees on a larger ADU are figured on its full size. Our calculator has a 2027 setting that shows the difference.

Source: California Legislative Information: SB 1117 (Chapter 809, Statutes of 2026), chaptered text (opens in new tab)

Impact feesPalo Alto

Palo Alto's impact fee sheet (as of August 17, 2026) keeps ADUs out of housing and traffic fees

Palo Alto's August 2026 impact fee information sheet exempts ADUs under 750 sq ft from all development impact fees. Larger ADUs pay only the community-facility fees (parks, community centers, libraries, public safety, general government), proportional to the primary unit's size.

Source: City of Palo Alto: Development Impact and In-Lieu Fees (as of August 17, 2026) (opens in new tab)

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Every place we cover, by county

Modeled fees for a 1,000 sq ft detached ADU. + means some fees (usually valuation-based building permits) aren’t in the total.

Santa Cruz County 5

Alameda County 2

San Francisco County 1

Santa Clara County 7

FAQ

ADU fees in California, briefly

Do ADUs pay impact fees in California?

Not at 750 sq ft of interior livable space or less (500 sq ft or less for a JADU), under Government Code section 66311.5. Above 750 sq ft, impact fees must be proportional to the size of the main home.

Do ADUs pay school fees?

Yes, at 500 sq ft or more. Districts charge their adopted developer fee per sq ft, usually capped at the State Allocation Board’s Level 1 rate ($5.38 per sq ft since January 28, 2026).

What fees still apply to a small ADU?

Building permit and plan check fees, construction taxes in some cities, planning review, and water or sewer connection charges for new detached units. These are not impact fees under state law.

How are these totals calculated?

From each jurisdiction’s published fee schedule, with every rate quoted from a saved copy of the official document. Where a fee depends on your project (such as construction valuation), we show the formula and leave it out of modeled totals until you enter the input in the calculator.