San Diego, CA Accessory Structures: ADU Impact Fees (2026)
Key Facts
- First 2 ADUs
- Exempt from impact fees
- ADUs under 750 sq ft
- Automatically exempt
- Owner-occupancy exemption
- 3-year signed affidavit required
- Fee due
- Before final inspection
Summary
San Diego waives development impact fees for the first two ADUs on a property and for any ADU under 750 square feet, removing one of the biggest cost barriers to building a backyard unit.
Accessory Dwelling Units less than 750 square feet in gross floor area, Junior Accessory Dwelling Units, movable tiny houses, and guest quarters are exempt from Development Impact Fees... The first two Accessory Dwelling Units on a premises shall be exempt from the requirement to pay Development Impact Fees, regardless of the gross floor area of the Accessory Dwelling Unit.
Full Breakdown
Under SDMC Section 142.0640(b)(1), Development Impact Fees are normally due before the city signs off on final inspection, but ADUs get built-in exemptions: any ADU under 750 square feet in gross floor area is exempt outright, and the first two ADUs on a lot are exempt regardless of size. A property owner can also skip the fee on a larger ADU by signing a recorded affidavit agreeing to live in one of the units for at least three years after the building permit issues.
Violations & Fines
Unpaid Development Impact Fees block final inspection, so the ADU cannot be legally occupied until the fee is paid or the exemption affidavit is properly recorded with the County Recorder.
Frequently Asked Questions
Do I have to pay a development impact fee for my ADU in San Diego?
Can I avoid the fee on a larger ADU?
Sources & Official References
Other rules in San Diego
California rules heatmap·Compare San Diego to another location·View the California accessory structures overview
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ADU Impact Fees in Nearby Cities
How other cities in San Diego County handle adu impact fees.