El Cajon, CA Accessory Structures: ADU Impact Fees (2026)
Key Facts
- Under 750 sq ft
- No development impact fees at all
- Over 750 sq ft
- Fee charged proportionate to unit size
- Governing fee chapter
- El Cajon Municipal Code Chapter 17.25
- Max standard ADU size
- 1,200 square feet habitable
- Max JADU size
- 500 square feet
Summary
El Cajon waives development impact fees entirely for any accessory or junior accessory dwelling unit under 750 square feet under § 17.140.180(G)(2); units larger than 750 square feet are charged impact fees only proportionately, based on the ADU's square footage relative to the primary dwelling.
Development Impact Fees; Applicability. Development Impact Fees for ADUs and JADUs shall comply with Chapter 17.25 Procedures, Hearings, Notices and Fees. Fee Waiver. In addition to the requirements in Chapter 17.25, ADUs or JADUs that are less than 750 square feet shall not be subject to any impact fees. Any impact fees charged for an ADU more than 750 square feet shall be charged proportionately in relation to the square footage of the primary dwelling unit.
Full Breakdown
180(G) governs fees for accessory and junior accessory dwelling units in two parts. " Subsection (G)(2), the fee waiver, goes further: any ADU or JADU under 750 square feet is not subject to any impact fees at all, and any impact fee charged for an ADU larger than 750 square feet must be calculated proportionately to the unit's square footage relative to the primary dwelling unit, rather than at the full flat rate applied to a new single-family home. 180(C)(2), the practical effect is that many smaller conversions and detached units, including garage conversions under 750 square feet, pay no development impact fee at all, while only larger ADUs between 750 and 1,200 square feet see a fee scaled down from the primary home's rate.
These fee provisions were adopted with the broader ADU ordinance under Ord. 5142 (5/28/2024) and remain current through Ord. 5148 (1/28/2025), Ord. 5151 (5/13/2025) and Ord. 5173 (2/10/2026).
Violations & Fines
There is no separate penalty tied to the fee waiver itself; the consequence of miscalculating or refusing to pay an applicable impact fee on an ADU over 750 square feet is that the building permit cannot be finalized until fees due under Chapter 17.25 are paid. Applicants who believe a fee was assessed contrary to the proportional formula in § 17.140.180(G)(2) can raise it through the permit review and hearings process set out in Chapter 17.25.
Frequently Asked Questions
Does my El Cajon ADU owe development impact fees?
How are impact fees calculated for a larger ADU?
Which chapter sets the actual impact fee amounts?
Sources & Official References
Other rules in El Cajon
California rules heatmap·Compare El Cajon to another location·View the California accessory structures overview
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