San Clemente, CA Accessory Structures: ADU Impact Fees (2026)
Key Facts
- No-fee threshold
- Under 750 square feet of interior livable space
- Fees apply at
- 750 square feet or more: impact fee and connection fee
- Fee formula
- ADU floor area divided by primary dwelling floor area, times typical new-dwelling fee
- ADU built with a new home
- Separate utility connection, proportional connection fee and capacity charge
- Conversions inside a dwelling
- No separate utility connection required
- Septic connection
- Percolation test within five years, or 10 if recertified
- Latest amendment
- Ord. No. 1810, adopted June 16, 2026
Summary
San Clemente charges no impact fee and no connection fee for an accessory dwelling unit with less than 750 square feet of interior livable space. A unit of 750 square feet or more pays both, scaled by the ADU's floor area compared with the floor area of the primary dwelling. Subsection F of Municipal Code § 17.28.270 sets the rule.
Impact and Utility Fees. 1. No impact fee or connection fee is required for an ADU that provides less than 750 square feet of interior livable space; 2. An impact fee and connection fee is required for an ADU that provides at least 750 square feet of interior livable space and shall be charged proportionately in relation to the square footage of the primary dwelling unit. (e.g., the floor area of the ADU, divided by the floor area of the primary dwelling, times the typical fee amount charged for a new dwelling); and 3. If an ADU is constructed at the same time as a new single-family or multi-family dwelling, a separate utility connection directly between the ADU and the utility shall be required and payment of the proportional connection fee and capacity charge shall be required. 4. Conversion. No separate connection between the accessory dwelling unit and the utility shall be required for units created within a single-family or multi-family dwelling(s).
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: Traffic: Supplement 30 | Code of Ordinances: Supplement 66 Update 1).
Full Breakdown
The fee rules sit in subsection F, titled Impact and Utility Fees, of San Clemente Municipal Code § 17.28.270, the Accessory Dwelling Units section of Chapter 17.28 (Special Uses) in the Zoning title. The section implements California Government Code Sections 66310-66342, and its history line shows the most recent amendment is Ord. No. 1810, adopted June 16, 2026, building on Ord. Nos. 1668 (2019), 1707 (2021), 1742 (2022) and 1759 (2023).
The dividing line is size. Under F.1, an ADU that provides less than 750 square feet of interior livable space owes no impact fee and no connection fee. Under F.2, an ADU that provides at least 750 square feet owes both. The fee is charged proportionately: the floor area of the ADU is divided by the floor area of the primary dwelling, and the result is multiplied by the typical fee amount charged for a new dwelling. A small ADU beside a large house therefore pays a small share of the new-dwelling fee, while a larger unit beside a modest house pays a bigger share.
The 750 square foot line sits close to the section's size caps. Under E.4, a detached or attached ADU is capped at 850 square feet of interior livable space for a studio or one-bedroom unit and 1,000 square feet for a unit with two or more bedrooms, and a junior accessory dwelling unit is capped at 500 square feet. Units between 750 and the cap fall inside the fee rule, and the text of subsection F speaks only of ADUs.
Utility connections are handled separately. Under F.3, when an ADU is built at the same time as a new single-family or multi-family dwelling, a separate utility connection directly between the ADU and the utility is required, along with payment of the proportional connection fee and capacity charge. Under F.4, a conversion needs no separate connection between the ADU and the utility when the unit is created within a single-family or multi-family dwelling.
Subsection F.5 covers septic. If the principal dwelling is connected to an on-site wastewater treatment system and cannot connect to a sewer system, the ADU or JADU can connect to the same system, but the application must include a percolation test completed within the last five years or, if recertified, within the last 10 years.
Violations & Fines
Subsection F prints no stand-alone penalty for unpaid fees. ADUs are approved subject to issuance of a building permit under subsection C, so the fee and connection requirements travel with the permit. Related enforcement appears in subsection G: an ADU cannot be rented for 30 days or less, and a JADU deed restriction is enforceable by the Planning Division, with legal action, an injunction or abatement of the illegal unit as available remedies.
Frequently Asked Questions
Does San Clemente charge impact fees on a small ADU?
How is the fee calculated for an ADU of 750 square feet or more?
What applies when the ADU is built together with a new house?
Does a converted garage or interior ADU need its own utility connection?
Can an ADU use the existing septic system in San Clemente?
Sources & Official References
Other rules in San Clemente
California rules heatmap·Compare San Clemente to another location·View the California accessory structures overview
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