Alameda County, CA Accessory Structures: ADU Impact Fees (2026)
Key Facts
- Fee waiver threshold
- Under 750 sq ft
- Junior ADUs
- Always fee-exempt
- Legalization relief
- No fee unless utility upgrade
- Governing section
- § 17.55.140
Summary
Unincorporated Alameda County waives park dedication impact fees for accessory dwelling units under 750 sq ft, and never charges them for junior accessory dwelling units, under Chapter 17.55.
No park dedication impact fees are required for accessory dwelling units measuring less than seven hundred fifty (750) square feet in interior livable space and no park dedication impact fees shall be required for junior accessory dwelling units.
Full Breakdown
Section 17.55.140 exempts small accessory dwelling units from the county's park dedication impact fee: any ADU under 750 sq ft of interior livable space owes no park fee, and junior ADUs are exempt regardless of size. A related provision, § 17.55.180(4), extends similar relief to homeowners legalizing a previously unpermitted ADU or JADU built before the state cutoff date, no impact, connection, or capacity fees unless utility upgrades are required to meet health and safety standards. Larger new-construction ADUs above 750 sq ft remain subject to the standard park dedication fee schedule.
Violations & Fines
Larger ADUs (750+ sq ft) billed as fee-exempt, or unpermitted-ADU legalizations charged connection fees without a documented health-and-safety utility upgrade, are fee disputes the planning department resolves under §§ 17.55.140 and .180.
Frequently Asked Questions
Do I owe a park fee for a 600 sq ft ADU?
What about a junior ADU?
Sources & Official References
Other rules in Alameda County
California rules heatmap·Compare Alameda County to another location·View the California accessory structures overview
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