ADU fees in Los Gatos: $2,068–$7,848 in modeled fees for 1,000 sq ft, plus valuation-based permits
Los Gatos prices its building permit from construction valuation using the International Code Council's valuation data, so the largest permit costs depend on your project. Per-sq-ft construction taxes and a $2 per sq ft storm drainage fee apply to new floor area and paving. ADUs of 750 sq ft or more also pay the Town's traffic impact fee, charged per new daily trip.
13 fee lines · 3 official sources · checked Oct 18, 2026 · Sources · Calculator
Totals leave out valuation-based building fees and traffic impact mitigation fee and building plan review, state title 24 energy/accessibility review at some sizes. Enter a construction valuation in the calculator to include them.
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 plan check of the building permit (20% of building fee)1
Building permit (valuation table)1The Town values new construction from ICC Building Valuation Data (February 2012) × a 2.32 regional modifier, indexed yearly; it doesn't publish the resulting $/sq ft, so enter your valuation in the calculator.
Needs valuation
Needs valuation
Needs valuation
Needs valuation
Building plan review (65% of building permit fee)1
Needs valuation
Needs valuation
Needs valuation
Needs valuation
State Title 24 energy/accessibility review (15% of building permit fee)1
Needs valuation
Needs valuation
Needs valuation
Needs valuation
General Plan update surcharge (0.5% of valuation)1
Needs valuation
Needs valuation
Needs valuation
Needs valuation
Seismic mapping fee (state, $13 per $100,000 of valuation)1
Needs valuation
Needs valuation
Needs valuation
Needs valuation
Construction taxes
Capital improvement tax ($0.18 per sq ft)1The schedule words it as new floor area of an existing building; whether the Town applies it to a new detached ADU isn't stated, so it counts in the high total only.
Storm drainage fee ($2.00 per sq ft of new impervious area)1We assume new impervious area equals the ADU's floor area (one story, no new paving). Patios and paths add to it.
Exempt
Exempt
Est.$2,000
Est.$2,400
Traffic impact mitigation fee ($1,128 per new daily trip)1Applies to ADUs of 750 sq ft or more. The fee schedule doesn't say how many daily trips the Town assigns an ADU, so we can't compute it.
Exempt
Exempt
Needs valuation
Needs valuation
School district fee
School fees (Los Gatos Union / Los Gatos-Saratoga High, or your district)4District rates not captured yet; shown at the 2026 statewide Level 1 maximum as an upper bound.
Exempt
Up to$4,035
Up to$5,380
Up to$6,456
Modeled total
$68–$268
$68–$4,403
$2,068–$7,848
$2,468–$9,404
Rules
What you can build in Los Gatos
Maximum size
1,200 sq ft. The Town adds 10% to the allowed floor area for an ADU, and an ADU up to 800 sq ft is allowed regardless of floor-area limits. 2
Height
16 ft detached; 18 ft near major transit (+2 ft for roof pitch) or with a multi-story multifamily home; 25 ft or the zone limit attached. 2
Setbacks
4 ft side and rear; front as for the main home. Detached ADUs can't go in front of the main home; 5 ft from other structures. 2
Parking
One space per ADU or per bedroom, whichever is less, with the state exceptions (for example near transit) where none is required. (Town FAQ dated November 2023.) 2
Owner occupancy
Not required for an ADU. With a JADU, the owner must live in the house or the JADU. 3
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 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
Los Gatos issued 128 ADU building permits in 2025
546 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.
Building permit, plan review, Title 24 and planning plan check fees depend on construction valuation, which the Town derives from ICC data it doesn't publish per sq ft. They're left out of modeled totals; the calculator includes them once you enter a valuation.
Traffic impact fee for ADUs of 750 sq ft or more: $1,128 per new daily trip, but the trip rate for an ADU isn't stated.
Engineering, encroachment and sewer (West Valley Sanitation District) and water connection charges aren't included.
School district rates not captured; shown at the statewide cap.
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 Los Gatos’s official fee schedules comes to $68–$4,403 at 750 sq ft and $2,068–$7,848 at 1,000 sq ft. These totals leave out valuation-based building fees and traffic impact mitigation fee and building plan review, state title 24 energy/accessibility review at some sizes. Ranges show fees that may or may not apply to your project.
Does Los Gatos 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 Los Gatos come to at most $2,000.
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 Los Gatos?
1,200 sq ft. The Town adds 10% to the allowed floor area for an ADU, and an ADU up to 800 sq ft is allowed regardless of floor-area limits.
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