ADU Impact Fees: Petaluma vs Sonoma
How do adu impact fees rules compare between Petaluma, CA and Sonoma, CA?
Petaluma, CA
Sonoma County
No data available yet for Petaluma.
Sonoma, CA
Sonoma County
Per Cal. Gov. Code 65852.2(f) and 66311.5, ADUs under 750 sq ft pay NO impact fees in Sonoma. ADUs 750 sq ft or larger pay impact fees proportionate to the ratio of ADU square footage to the primary dwelling's square footage, collected at final inspection or certificate of occupancy.
View full Sonoma rules →Key Facts Comparison
| Fact | Petaluma | Sonoma |
|---|---|---|
| Impact fees under 750 sq ft | - | $0 (state-prohibited) |
| Impact fees 750+ sq ft | - | Proportional to primary dwelling |
| Collection timing (750+ sq ft) | - | Final inspection / CofO |
| School fees | - | Apply at 500+ sq ft, proportional |
| State authority | - | Cal. Gov. Code 66311.5; 65852.2(f) |
Highlighted rows indicate differences between cities.
Petaluma FAQ
No FAQs available.
Sonoma FAQ
Will I owe impact fees on a 700 sq ft ADU in Sonoma?
No. Cal. Gov. Code 66311.5 prohibits local agencies, special districts, and water corporations from charging any impact fee on an ADU under 750 sq ft. The City of Sonoma follows this rule in SMC 19.45.040.
How much are impact fees on a 900 sq ft ADU?
Fees are proportional: if your primary dwelling is 1,800 sq ft, your 900 sq ft ADU pays 50% of the equivalent new-construction impact fees. SMC 19.45.040 codifies this proportionality, and fees are collected at final inspection per AB 671.
Do school impact fees apply?
School impact fees under Ed. Code 17620 can apply to ADUs of 500 sq ft or more, but California HCD guidance requires they also be proportional. Confirm the current rate with the local school district at permit submittal.
Compare other topics
See how Petaluma and Sonoma compare on other ordinance categories.
Want to add a third city?
Use our full comparison tool to compare up to three cities.
Open Comparison Tool