Los Banos, CA Accessory Structures: ADU Impact Fees (2026)
Key Facts
- Impact fee, ADU under 750 sq ft
- none
- Impact fee, ADU 750 sq ft+
- proportional to primary dwelling
- Excludes
- connection fees, capacity charges
- Includes
- Gov. Code § 66477 fees
- Governing section
- § 9-3.3009
Summary
An accessory dwelling unit under 750 square feet pays no development impact fees at all in Los Banos. Municipal Code § 9-3.3009 waives impact fees below that threshold and, above it, charges fees only in proportion to the ADU's size relative to the primary dwelling, not the flat rate a new single-family home would pay.
No impact fee shall be imposed upon the development of an accessory dwelling unit that is less than 750 square feet. Any impact fees charged for an accessory dwelling unit of 750 square feet or more shall be charged proportionately in relation to the square footage of the primary dwelling unit (e.g., the floor area of the primary dwelling, divided by the floor area of the accessory dwelling unit, times the typical fee amount charged for a new dwelling). For purposes of this section, "impact fee" has the same meaning as the term "fee" is defined in subdivision (b) of Section 66000 of the Government Code, except that it also includes fees specified in Section 66477. "Impact fee" does not include any connection fee or capacity charge.
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: rev 4356507; v3 updated 2025-03-05).
Full Breakdown
3009 writes the state-law impact fee formula for ADUs directly into the Los Banos code. Units smaller than 750 square feet, which covers many attached conversions and smaller detached units, are exempt from impact fees entirely; no impact fee can be imposed on a project under that threshold. Once an ADU reaches 750 square feet or more, the City cannot charge it the same flat impact fee as a new single-family home. Instead, the fee must be calculated proportionately: divide the floor area of the primary dwelling by the floor area of the ADU, then apply that ratio to the standard fee charged for a new dwelling, so a small ADU attached to a large house pays only a fraction of what a full new home would owe. 3008 and can still be charged for water, sewer, and electric hookups regardless of the ADU's size.
Violations & Fines
An impact fee assessed on an ADU under 750 square feet, or one charged at the full new-dwelling rate rather than the proportional formula in § 9-3.3009, exceeds what the City is authorized to collect and can be challenged as a fee imposed contrary to the section's express terms.
Frequently Asked Questions
Do I pay impact fees on a small Los Banos ADU?
How is the impact fee calculated for a larger ADU?
Are utility connection fees included in the ADU impact fee waiver?
Sources & Official References
Other rules in Los Banos
California rules heatmap·Compare Los Banos to another location·View the California accessory structures overview
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