ADU fees in San José: $14,045–$29,202 for a 1,000 sq ft backyard unit
San José charges flat ADU building fees in two size bands, plus valuation-based construction taxes that add more than the permit fees themselves. Parkland fees apply above 750 sq ft and vary by zone.
12 fee lines · 5 official sources · checked Oct 18, 2026 · Sources · Calculator
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
Planning review of the building permit1$398 plus the 13% citywide planning fee ($51). The schedule doesn't say which planning check an ADU gets, so it counts toward the high total only.
ADU plan review1Modular ADUs pay 10% less for plan review. If review takes longer than the table assumes, the City can bill the extra hours.
$1,137
$1,137
$1,950
$1,950
ADU inspection (incl. meter release)1Modular ADUs pay 20% less for inspection.
$1,732
$1,732
$2,520
$2,520
Fire plan check + inspection1$814 plan check + $455 inspection: the Fire Department's R-3 "custom single family" base fees. We're not sure Fire reviews every ADU this way, so it counts toward the high total only.
May apply$1,269
May apply$1,269
May apply$1,269
May apply$1,269
Construction taxes
Building & Structure Construction Tax (1.54% of valuation)1Valuation = ADU sq ft × $175.92, the City's R-3 valuation rate effective July 1, 2026. The City's taxes page mentions exemptions for some projects; we found none for ADUs.
Est.$1,352
Est.$2,032
Est.$2,709
Est.$3,251
Commercial-Residential-Mobilehome Park Construction Tax (2.42%)1
Est.$2,124
Est.$3,193
Est.$4,257
Est.$5,109
Construction Tax + Residential Construction Tax (per unit)1$114.00 + $136.80 at the 2-family rate, up to $150.00 + $180.00 at the 1-family rate. The schedule doesn't say which rate an ADU pays.
$251–$330
$251–$330
$251–$330
$251–$330
State SMIP + building standards fees10.01% (SMIP, residential) + 0.004% (building standards) of valuation.
Est.$12
Est.$18
Est.$25
Est.$30
Impact fees
Parkland impact fee (ADUs over 750 sq ft)2A flat fee per ADU set by zone: $1,700 to $8,900. The City still links this ADU parkland map, which dates from 2020; ask Parks for the current rate. Under state law an ADU of exactly 750 sq ft owes $0.
Exempt
Exempt
$1,700–$8,900
$1,700–$8,900
School district fee
School impact fee (your district)6About 19 school districts serve San José. We show the statewide Level 1 maximum as an upper bound. The City's ADU FAQ says school fees don't apply under 750 sq ft; the statewide exemption is under 500 sq ft, so ask your district.
Exempt
Up to$4,035
Up to$5,380
Up to$6,456
Utility connections
Sewage treatment plant connection1Per-unit rates for a single-family ($780) or multifamily ($438) dwelling. State law bars this charge for ADUs built within existing space, and only allows a proportional charge for new detached ADUs (Gov. Code 66311.5(d)–(e)). The schedule has no ADU rate, so it counts toward the high total only.
May apply$780
May apply$780
May apply$780
May apply$780
Modeled total
$7,030–$9,608
$8,785–$15,397
$14,045–$29,202
$15,443–$31,676
Water & sewer
Water comes from San José Water, the City's Municipal Water System or Great Oaks Water, depending on the address. Each sets its own meter and connection rules. The fee schedule's sewage treatment plant connection rates are shown above as a possible charge. 1
Rules
What you can build in San José
Maximum size
Detached ADU: 1,000 sq ft on lots under 9,000 sq ft; 1,200 sq ft on lots over 9,000 sq ft. JADU: 500 sq ft. 3
Height
Detached ADU: 18 ft for one story, 25 ft for a second story; up to 2 stories. 3
Setbacks
Side and rear: 4 ft. Front: the zoning district's setback (Table 20-60). Behind the main home or 45 ft from the front; max 40% rear-yard coverage; 6 ft between buildings. 3
Not required for an ADU. Owner-occupancy of the main home is required for a JADU that shares sanitation. 3
Pre-approved plans
San José runs a Preapproved ADU program of plans already reviewed by the City. 4
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 start at 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 José issued 502 ADU building permits in 2025
3,338 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.
Which planning and fire review an ADU gets (counted in the high total only).
Your parcel's parkland fee zone ($1,700–$8,900 range shown).
School district rates (statewide Level 1 maximum shown instead).
Water meter and connection charges from your water company.
Public Works storm and sanitary sewer fees, which the schedule lists per lot and doesn't address for ADUs.
Conflicting official statements
The City's ADU FAQ says school impact fees don't apply to ADUs under 750 sq ft. State law only exempts ADUs under 500 sq ft from school fees (Gov. Code 66311.5(c)(3)); confirm with your district.
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.
San José's Building Division fee schedule effective August 10, 2026 sets ADU building permit fees in two size bands (up to 750 sq ft, and 751–1,200 sq ft) for issuance, plan review and inspection. Our San José figures use it.
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.
For a detached ADU with a 2,000 sq ft main home (an example assumption), our model of San José’s official fee schedules comes to $8,785–$15,397 at 750 sq ft and $14,045–$29,202 at 1,000 sq ft. Ranges show fees that may or may not apply to your project.
Does San José 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. At 1,000 sq ft, the impact fees we model for San José come to at most $8,900.
Do school fees apply to an ADU?
Only at 500 sq ft or more. 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.
How big can an ADU be in San José?
Detached ADU: 1,000 sq ft on lots under 9,000 sq ft; 1,200 sq ft on lots over 9,000 sq ft. JADU: 500 sq ft.
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