Junior ADU (JADU) · checked Oct 18, 2026
Junior ADU fees in Santa Clara: $4,319–$4,813 for a 500 sq ft JADU
A junior ADU of up to 500 sq ft inside the house pays no impact fees, no school fees and no new utility connection charge under state law. What’s left in Santa Clara is permit and review work: building permit & plan check $3,620, planning & zoning $699, public works & encroachment $0–$494.
Santa Clara’s schedule
What Santa Clara’s documents say about junior ADUs
- Architectural review: ADU / JADU (Planning)
Accessory Dwelling Unit / Junior $ 306.00 Yes
We model a junior ADU as a conversion of space inside the home, using the same schedule lines as an ADU. Where the City charges a JADU less, that’s noted above.
Line by line: junior ADU vs new detached ADU at 500 sq ft
Law in force today. The detached column is for comparison only.
| Fee | Junior ADU, 500 sq ft | New detached ADU, 500 sq ft |
|---|---|---|
| Planning & zoning | ||
| Architectural review: ADU / JADU (Planning) | $306 | $306 |
| General Plan / Advanced Planning surcharge | $393 | $393 |
| Building permit & plan check | ||
| Building plan review (scaled by size) | $1,610 | $1,610 |
| Building permit (scaled by size) | $1,560 | $1,560 |
| Permit issuance fee | $101 | $101 |
| Electrical permit (residential, per sq ft) | $120 | $120 |
| Mechanical permit (new residential, per sq ft) | $50 | $50 |
| Plumbing permit (new residential, per sq ft) | $50 | $50 |
| Technology fee | $128 | $128 |
| Public works & encroachment | ||
| Cost Analysis for Development, minor (Public Works) | May apply$494 | May apply$494 |
| School district fee | ||
| School fee (district; statewide cap shown) | Exempt | Exempt |
| Utility connections | ||
| Sanitary sewer conveyance fee (ADU 750 sq ft and larger) | n/a | n/a |
| Wastewater treatment plant capacity fee (per ADU) | Exempt | $747 |
| Modeled total | $4,319–$4,813 | $5,066–$5,560 |
State law
The rules for a junior ADU
One per single-family lot, inside the house (an attached garage counts), up to 500 sq ft with an efficiency kitchen. No extra parking; owner occupancy only if it shares a bathroom.
Gov. Code §66313(d)
“Junior accessory dwelling unit” means a unit that is no more than 500 square feet of interior livable space in size and contained entirely within a single-family residence.
Gov. Code §66333(a)
Limit the number of junior accessory dwelling units to one per residential lot zoned for single-family residences with a single-family residence built, or proposed to be built, on the lot.
Gov. Code §66333(d)
For purposes of this subdivision, enclosed uses within the residence, such as attached garages, are considered a part of the proposed or existing single-family residence.
Gov. Code §66333(f)
Require the permitted junior accessory dwelling unit to include an efficiency kitchen
Gov. Code §66334(a)
A junior accessory dwelling unit ordinance adopted pursuant to Section 66333 shall not require additional parking as a condition to grant a permit.
Gov. Code §66333(b)
Owner-occupancy shall not be required if the junior accessory dwelling unit has separate sanitation facilities, or if the owner is another governmental agency, land trust, or housing organization.
Quoted from Government Code, Title 7, Division 1, Chapter 13 (Accessory Dwelling Units), incl. §66311.5 (opens in new tab), checked Oct 18, 2026.
FAQ
Questions about junior ADUs in Santa Clara
How much are junior ADU fees in Santa Clara?
Our model of Santa Clara’s official schedules comes to $4,319–$4,813 for a 500 sq ft junior ADU, compared with $5,066–$5,560 for a new detached ADU of the same size.
Do junior ADUs pay impact or school fees?
No. State law bars impact fees on a junior ADU of 500 sq ft or less (Gov. Code §66311.5(c)(1)), and school fees apply only when a project adds more than 500 sq ft of assessable space (Ed. Code §17620; Gov. Code §66311.5(c)(3)).
Can I build a junior ADU and an ADU on the same lot?
Yes. On a single-family lot, state law requires cities to approve one ADU and one junior ADU, plus a detached ADU of up to 800 sq ft (Gov. Code §66323(a)).
Do I have to live on the property?
Only if the junior ADU shares a bathroom with the main house. With its own bathroom, no owner-occupancy rule applies (Gov. Code §66333(b)).
Not modeled yet
What these totals leave out
- The schedule doesn’t say whether park in-lieu or traffic impact fees apply to ADUs. State law makes any such fee $0 at 750 sq ft or less and proportional to the main home above.
- Building Conformance Fee (valuation × $0.00032), Silicon Valley Power service fees and the sanitary sewer outlet charge per lot aren’t included.
- Fees are rounded down to the nearest nickel under the July 7, 2026 amendment (Resolution 26-9584); we use the amounts printed in the schedule.
More
Keep going
Sources
Official sources
Every figure comes from these documents; each line’s quoted text is on the Santa Clara page.
- City of Santa ClaraFY 2026/27 Municipal Fee Schedule (adopted April 21, 2026; Building Division amended July 7, 2026) (opens in new tab)
- California State Allocation Board (Department of General Services, OPSC)State Allocation Board item: 2026 adjustment to the Level I developer fee (meeting of January 28, 2026) (opens in new tab)
- California Legislative Information (leginfo.legislature.ca.gov)Government Code, Title 7, Division 1, Chapter 13 (Accessory Dwelling Units), incl. §66311.5 (opens in new tab)
- HCD via data.ca.govHousing Element Annual Progress Report (APR) data, Table A2: ADU building permits by year (opens in new tab)