ADU fees in San Diego: $16,137–$21,682 in modeled fees for 1,000 sq ft, before water and sewer capacity fees
San Diego exempts the first two ADUs on a lot from its Development Impact Fees, at any size, so a typical ADU pays no city impact fee. The big cost is building plan check and inspection: about $5,350 for a detached ADU up to 500 sq ft and about $15,370 above that, from the City’s published Table 501A. Water and sewer capacity fees are set per EDU during review and aren’t modeled.
8 fee lines · 3 official sources · checked Oct 18, 2026 · Sources · Calculator
Totals leave out water and sewer capacity fees.
Modeled fees by ADU size
Detached ADU, 2,000 sq ft main home (example assumption), law in force today. Bars: solid = fees that apply, hatched = fees that may apply.
Each fee with its official source (numbers link to the source list). Est. = computed by us from the official rate; May apply = high total only; Up to = statewide cap, district may charge less.
Fee
499 sq ft
750 sq ft
1,000 sq ft
1,200 sq ft
Planning & zoning
General Plan Maintenance Fee1Collected once per project at application. The City’s ADU bulletin says it applies to all ADUs and JADUs.
$737
$737
$737
$737
Building permit & plan check
Mapping Fee1Charged when plans or maps are used for project review.
$11
$11
$11
$11
Building plan check (Table 501A)1Detached ADU up to 500 sq ft: the Add/Remodel row ($3,275.45). Detached ADU over 500 sq ft: the single-dwelling row ($7,538.70). Attached ADUs and conversions up to 1,100 sq ft: $3,275.45 plus $6.51 per sq ft over 500. A converted detached accessory structure over 500 sq ft may be charged the single-dwelling row instead.
$3,275
$7,539
$7,539
$7,539
Building inspection (Table 501A)1Collected at permit issuance, from the same rows as plan check.
$2,078
$7,834
$7,834
$7,834
Water/sewer plan check (no meter change)1Charged when a water and sewer review is performed; a new or upgraded meter is $329.26 per EDU instead.
May apply$165
May apply$165
May apply$165
May apply$165
Fee collection (other agencies)1Once per project, for fees DSD collects for others (state fees, water/sewer).
$16
$16
$16
$16
Impact fees
Development Impact Fees (DIF)3The first two ADUs on a lot are exempt at any size; a third or later ADU of 750 sq ft or more pays the multiple-dwelling rate.
State floor: cities must allow at least 850 sq ft (1,000 sq ft with 2+ bedrooms); detached ADUs can be capped at 1,200 sq ft. Local rule not captured yet.5
Height
State floor: 16 ft detached (18 ft near transit or on a multifamily lot, +2 ft for roof pitch); 25 ft attached. Local rule not captured yet.5
Setbacks
State limit: no more than 4 ft side and rear. Local rule not captured yet.5
Parking
State limit: at most 1 space per ADU or bedroom, and none within ½ mile of transit and in other cases. Local rule not captured yet.5
Owner occupancy
State law: cities can't require the owner to live on site for an ADU (JADUs: owner on site if sanitation is shared). Local rule not captured yet.5
Pre-approved plans
State law: every city must run a program to pre-approve ADU plans (Gov. Code 65852.27). Local rule not captured yet.5
State law
Why a 750 sq ft ADU pays no impact fees
California bars impact fees on ADUs of 750 sq ft or less of interior livable space. Above that, they must be proportional to the main home’s size; we assume 2,000 sq ft unless you enter yours. School fees apply only above 500 sq ft. From January 1, 2027, SB 1117 limits impact fees to the area over 750 sq ft. How the state rules work →
ADU permits issued
San Diego issued 2,165 ADU building permits in 2025
9,225 from 2018 to 2025, as the jurisdiction reported to the state in its Housing Element Annual Progress Reports (Table A2, ADU rows; may include JADUs). “–” means no ADU rows were reported that year.
The Governor approved SB 1117 (Chapter 809, Statutes of 2026) on September 29, 2026. It amends Gov. Code 66311.5: on lots with up to two ADUs, impact fees on an ADU over 750 sq ft must still be proportional to the primary home, and may only be charged on the area over 750 sq ft. Regular 2026 statutes take effect January 1, 2027. Until then, fees on a larger ADU are figured on its full size. Our calculator has a 2027 setting that shows the difference.
The Department of Housing and Community Development updated its ADU Handbook to reflect the laws that took effect January 1, 2026. Its proportional-fee example: a 1,000 sq ft ADU next to a 2,000 sq ft home pays 50% of the fee a new home would pay. Our models use 2,000 sq ft as the example primary-home size unless you enter your own.
On January 28, 2026 the State Allocation Board raised the statewide maximum Level 1 developer fee for residential construction from $5.17 to $5.38 per sq ft (+4.06%). School districts collect it on ADUs of 500 sq ft or more, at their own adopted rate up to this cap (higher Level 2/3 fees need extra findings). Where we haven't confirmed a district's rate, we use $5.38 as the upper bound.
SB 543 (Chapter 520, Statutes of 2025) took effect January 1, 2026. It restates the impact-fee rule in Gov. Code 66311.5: no impact fees on an ADU of 750 sq ft of interior livable space or less, or a JADU of 500 sq ft or less; above that, fees must be proportional to the primary home. It also caps JADUs at 500 sq ft of interior livable space. Many city documents still cite the older section numbers (65852.2 or 66324).
For a detached ADU with a 2,000 sq ft main home (an example assumption), our model of San Diego’s official fee schedules comes to $16,137–$20,337 at 750 sq ft and $16,137–$21,682 at 1,000 sq ft. These totals leave out water and sewer capacity fees. Ranges show fees that may or may not apply to your project.
Does San Diego charge impact fees on a 750 sq ft ADU?
No. California Government Code section 66311.5 bars impact fees on an ADU of 750 sq ft of interior livable space or less (500 sq ft or less for a JADU). Above 750 sq ft, impact fees must be proportional to the size of the main home.
Do school fees apply to an ADU?
Only above 500 sq ft. School districts charge their adopted developer fee per sq ft, capped at the State Allocation Board’s Level 1 maximum ($5.38 per sq ft since January 28, 2026) unless they qualify for higher levels.
Res-SDU/DUP 1 $7,538.70 - $7,833.94 - (Single Dwelling Unit /Duplex/detached Group R-3 ADU over 500 or addition/remodel, including attached 3,000 $7,538.70 $3.82 $7,833.94 $3.93 ADU/JADU over 1,100 SF)
Res-SDU/DUP Add/Remodel 1 $3,275.45 - $2,077.66 - (Residential-Single Dwelling Unit/Duplex Addition/Remodel, including attached ADU/JADU to 1,100 SF 500 $3,275.45 $6.51 $2,077.66 $4.16 and detached ADU up to 500 SF)
SDU/Duplex/Townhome, No Water Meter Change EA $164.63
Development Services assesses a Water and Sewer Plan Check Fee when a water and sewer review of any type is performed.
A $15.95 fee is charged for fees collected by DSD or other departments/agencies (e.g., water/sewer fees, Affordable Housing In-lieu, construction debris recycling, State fees, lead hazard fee). The fee is charged at permit issuance, and once per project.
A local agency, special district, or water corporation shall not impose any impact fee upon the development of an accessory dwelling unit that has 750 square feet of interior livable space or less