ADU fees

ADU permit and impact fees in California

Fees can be a real part of an ADU budget, and they're one of the places where California law does the most to help homeowners. Here's what state law says about impact fees, utility connection fees, and school fees for ADUs and junior ADUs (JADUs), what your city still charges, and a few real city fee schedules so you can see how it works in practice.

Last reviewed October 19, 2026

1 · The short answer

Short answer

Impact fees: A city, county, special district, or water corporation can't charge impact fees on an ADU with 750 square feet of interior livable space or less, or on a JADU with 500 square feet or less. For an ADU over 750 square feet, impact fees must be proportional to the size of the main home. This is Gov. Code §66311.5(c), in effect since January 1, 2026.
Utility connection fees: An ADU or JADU isn't treated as a new residential use for water and sewer connection fees or capacity charges, unless it's built along with a new single-family home. ADUs created inside existing space can't be required to get a new or separate utility connection or pay a related fee. Other ADUs can be required to have a separate connection, with a fee proportionate to the ADU's burden on the system.
School fees: School districts may charge fees on ADUs over 500 square feet. ADUs and JADUs under 500 square feet don't count as adding enough space to trigger them.
Permit and plan check fees still apply. Each city sets its own building permit, plan check, and inspection fees.

Sources: Cal. Gov. Code §66311.5 (ADU and JADU fees) · Cal. Ed. Code §17620 (school district fees) · HCD ADU Handbook (March 2026, PDF)

2 · The section number

Which section of the law? (66311.5, not 66324)

If you've read that ADU fees are in Gov. Code §66324, that was true until the end of 2025. The fee rules have moved twice:

When	Where the ADU fee rules were	What changed
January 1, 2020	Gov. Code §65852.2(f)	SB 13 (2019) set the 750 sq ft line: no impact fees on an ADU less than 750 sq ft; proportional fees for 750 sq ft or more.
March 25, 2024	Gov. Code §66324	SB 477 (2024) reorganized and renumbered the state ADU law. The State Board of Equalization describes it as making nonsubstantive changes.
January 1, 2026	Gov. Code §66311.5	SB 543 (2025) moved the section and changed the wording to ADUs of 750 sq ft of interior livable space or less (exempt) and more than 750 sq ft (proportional). It added the same exemption for JADUs of 500 sq ft or less.

SB 13 was part of a 2019 package of ADU bills with AB 68 and AB 881 that also, among other things, cut the time cities have to act on an ADU application from 120 days to 60 days.

Practical tip: some city web pages still cite the old sections or the old "less than 750" wording. If your ADU is exactly 750 square feet, current state law treats it as exempt. If your city's page says otherwise, ask them about it.

Sources: Cal. Gov. Code §66311.5 (ADU and JADU fees) · Cal. Gov. Code §66324 (former ADU fee section) · SB 543 (2025), chaptered bill text · SB 13 (2019), chaptered bill text · AB 68 (2019), chaptered bill text · HCD ADU Handbook (March 2026, PDF) · HCD, Accessory Dwelling Units page · Board of Equalization, Letter To Assessors No. 2024/014 (PDF)

3 · Fee types

The types of fees you may see

Fee	Who charges it	What state law says for ADUs
Impact fees (also called development impact fees, DIF, public facilities fees, park or Quimby fees)	City, county, special district, water corporation	None for ADUs of 750 sq ft or less or JADUs of 500 sq ft or less; proportional above 750 sq ft (Gov. Code §66311.5(c))
Water and sewer connection fees and capacity charges	City, special district, or water company	Limited; depends on whether the ADU is inside existing space (Gov. Code §66311.5(b), (d), (e))
School fees	School district(s)	Allowed on ADUs over 500 sq ft; not on ADUs or JADUs under 500 sq ft (Ed. Code §17620; Gov. Code §66311.5(c)(3))
Building permit, plan check, and inspection fees	City or county building department	Set locally. State law also requires all ADU fees to follow the Mitigation Fee Act and related chapters (Gov. Code §66311.5(a))

State law also says the Legislature intends local ADU rules on fees not to be "so arbitrary, excessive, or burdensome" that they unreasonably restrict homeowners' ability to create ADUs (Gov. Code §66311).

Sources: Cal. Gov. Code §66311.5 (ADU and JADU fees) · Cal. Gov. Code §66311 (fee provisions not arbitrary, excessive, or burdensome) · Cal. Gov. Code §66000 (Mitigation Fee Act) · Cal. Ed. Code §17620 (school district fees)

4 · Impact fees

Impact fees: the 750 square foot rule

ADUs of 750 square feet or less: no impact fees. A local agency, special district, or water corporation can't impose any impact fee on an ADU with 750 square feet of interior livable space or less. The same goes for a JADU with 500 square feet of interior livable space or less.

ADUs over 750 square feet: proportional fees. Any impact fees charged on an ADU over 750 square feet must be proportional to the square footage of the main home. HCD's example: with a 2,000 sq ft main home and a 1,000 sq ft ADU, the ADU could be charged 50% of the impact fee for a new main home on the same site.

What counts as an impact fee. For this rule, "impact fee" means a fee under the Mitigation Fee Act (Gov. Code §66000(b)), which is a charge other than a tax or special assessment collected to pay for public facilities related to the project. It also includes park (Quimby) fees under Gov. Code §66477. It doesn't include utility connection fees or capacity charges, which have their own rules (next section).

Livable space. State ADU law defines livable space as space in a dwelling intended for human habitation, including living, sleeping, eating, cooking, or sanitation. HCD's Handbook adds that it includes bedrooms, bathrooms, kitchens, laundry rooms, closets, and interior stairs.

Some cities go further than state law. For example, Pasadena exempts ADUs of 900 square feet or less from its Residential Impact Fee, and San Diego exempts the first two ADUs on a property from its development impact fees regardless of size (see the city examples below).

Sources: Cal. Gov. Code §66311.5 (ADU and JADU fees) · Cal. Gov. Code §66000 (Mitigation Fee Act) · Cal. Gov. Code §66313 (livable space) · HCD ADU Handbook (March 2026, PDF) · City of San Diego, Public Spaces FAQ · City of Pasadena, Accessory Dwelling Units page

5 · Utilities

Water and sewer connection fees

State law treats these separately from impact fees:

Not a "new residential use." A local agency, special district, or water corporation can't treat an ADU or JADU as a new residential use when calculating connection fees or capacity charges, unless the unit was built with a new single-family home.
ADUs and JADUs inside existing space. For the units described in Gov. Code §66323(a)(1) (an ADU or JADU within the proposed or existing space of a single-family home or an existing accessory structure, with an expansion of up to 150 square feet for access), the agency can't require a new or separate utility connection or charge a related connection fee or capacity charge. The exceptions are a unit built with a new single-family home, or an ADU that's later sold separately under Gov. Code §66342.
Other ADUs (for example, most new detached ADUs). The agency may require a new or separate connection. If it does, the connection fee or capacity charge must be proportionate to the ADU's burden on the water or sewer system, based on either its square footage or its plumbing drainage fixture unit (DFU) values, and can't exceed the reasonable cost of providing the service.

Your water and sewer provider may be a different agency from your city. Ask each one.

Sources: Cal. Gov. Code §66311.5 (ADU and JADU fees) · Cal. Gov. Code §66323 (ADUs inside existing space) · HCD ADU Handbook (March 2026, PDF)

6 · School fees

School fees

Who: school districts. They're allowed, but not required, to charge school facility fees on construction in their boundaries (Ed. Code §17620). A property can be in more than one district. Chula Vista, for example, says school fees there are calculated by both the Sweetwater Union High School District and the Chula Vista Elementary School District.
ADUs under 500 square feet: For school fees, an ADU or JADU with less than 500 square feet of interior livable space is treated as residential construction that doesn't increase assessable space by 500 square feet, so it isn't charged (Gov. Code §66311.5(c)(3); Ed. Code §17620(a)(1)(C)). HCD's Handbook says school districts may charge fees on ADUs larger than 500 square feet.
How much: School fees are charged per square foot. The State Allocation Board raised the statewide maximum "Level I" residential fee to $5.38 per square foot on January 28, 2026 (it was $5.17 from 2024). A district can charge Level I only after adopting a study that justifies it, and some districts qualify for higher "Level II" or "Level III" fees under separate rules. Your district may charge less than the maximum, or more if it qualifies for a higher level.
When: A city or county generally can't issue a building permit until the school district certifies that its fee has been paid or doesn't apply (Ed. Code §17620(b)).

For a sense of scale only: at the Level I maximum, 1,000 square feet of assessable space would come to $5,380 (our arithmetic: 1,000 × $5.38). How your building department measures assessable space, and which level your district charges, can change that.

Sources: Cal. Ed. Code §17620 (school district fees) · Cal. Gov. Code §66311.5 (ADU and JADU fees) · Cal. Gov. Code §65995 (school facility fee caps) · State Allocation Board item, Index Adjustment on the Assessment for Development (January 28, 2026, PDF) · DGS/OPSC, Annual Adjustment to SFP Grants and Developer Fee History · HCD ADU Handbook (March 2026, PDF) · City of Chula Vista, Accessory Dwelling Units page

7 · Permit fees

Permit, plan check, and inspection fees

These are the fees your city or county charges to review plans and inspect the work. State ADU law doesn't set the amounts. Each city publishes its own fee schedule, and the method differs. Pasadena, for example, says its building permit fees are valuation-based, using the International Code Council's Building Valuation Data table. Chula Vista lists flat ADU permit fees by ADU type (example below).

Some cities offer standard or pre-designed ADU plans with lower review fees. Chula Vista says applicants using its standard ADU plans pay about $1,000 less in plan review fees than for a full submittal.

Sources: City of Pasadena, Permit Center Fee Schedules · City of Chula Vista, Fee Bulletin 10-400 (September 2024) · City of Chula Vista, Accessory Dwelling Units page

8 · City examples

Chula Vista

These city sections show how a few cities apply the rules. They're examples, not a list of every fee in those cities, and amounts change. Check the city's current schedule.

Building permit fees for ADUs, from the city's Fee Bulletin 10-400 (dated September 2024; the version linked from the city's ADU page when we checked):

Chula Vista Fee Bulletin 10-400

ADU type	Intake	Plan check	Inspection	Total
Detached, standard plan	$476	$533	$2,942	$3,951
Detached, nonstandard, up to 1,200 sq ft	$546	$1,475	$2,942	$4,963
Attached, first story, first 300 sq ft	$476	$634	$1,270	$2,380
Attached, first story, each additional 300 sq ft	$0	$211	$212	$423
Garage conversion to ADU, first 400 sq ft	$476	$423	$705	$1,604
Garage conversion, each additional 400 sq ft	$0	$52	$106	$158

Development impact fees, school fees, and utility fees are separate. Chula Vista's ADU page says JADUs and ADUs under 750 square feet are exempt from development impact fees, that ADUs of 750 square feet and above pay proportionally, and that a DIF figure is given during plan check. Its page cites the pre-2024 section number (Gov. Code §65852.2(f)(3)(A)); current state law (§66311.5) exempts ADUs of 750 square feet or less. The city also says most impact fees can be deferred to final inspection, and that DIF rates are indexed every October 1.

Sources: City of Chula Vista, Fee Bulletin 10-400 (September 2024) · City of Chula Vista, Accessory Dwelling Units page · Cal. Gov. Code §66311.5 (ADU and JADU fees)

9 · City examples

San Diego (city)

The City of San Diego says ADUs under 750 square feet are exempt from its development impact fees (DIF), and that the first two ADUs on a property are exempt from DIF regardless of size (San Diego Municipal Code §142.0640(b)(1)). Additional ADUs of 750 square feet or more pay DIF at the multiple-dwelling rate. The city's ADU bulletin (Information Bulletin 400, January 2026) also says ADUs and JADUs pay school fees, that the General Plan Maintenance Fee applies to all ADUs and JADUs, and that projects with more than one ADU pay Regional Transportation Congestion Improvement Program fees.

Sources: City of San Diego, Public Spaces FAQ · City of San Diego, Information Bulletin 400 (January 2026)

10 · City examples

Pasadena

For ADUs on single-family sites, Pasadena says:

ADUs of 900 square feet or less are exempt from its Residential Impact Fee (RIF) and get a 25% reduction in the Construction Tax, General Plan Maintenance Fee, and Technology Fee.
ADUs over 900 square feet pay a RIF proportional to the size of the main home, unless they have a Housing Agreement.
ADUs of any size with an executed Housing Agreement (an optional ADU Landlord Agreement or ADU Affordability Covenant, each for at least seven years), and ADUs built from a city Standard Plan, get 50% off plan check fees and are exempt from the RIF.
The construction and demolition (C&D) deposit for ADUs is reduced to $1,000.
The reductions aren't retroactive, a Housing Agreement must be signed before the permit is issued, and multi-family sites don't qualify.

Sources: City of Pasadena, Accessory Dwelling Units page

11 · City examples

Sierra Madre

Starting with applications received on or after July 1, 2026, Sierra Madre charges Public Facilities Fees on ADUs over 750 square feet (Resolution 26-50). The city's notice lays out the steps:

Start with the base amount. For FY 2026-27, the single-family base total is $76,393.44 (seven categories: general government, library, public safety, parks/Quimby, traffic, water, and sewer). The multi-family rate ($37,296.47) applies if the ADU is in a zone that allows multifamily housing.
Reduce it in proportion to the size of the ADU compared with the main home, under Gov. Code §66311.5.
Multiply by 0.25 if the property has no existing ADUs, 0.75 if it has one, or 1.00 if it has two or more.

Following those published steps, a 1,000 sq ft ADU next to a 2,000 sq ft home on a single-family lot with no other ADUs would come to $9,549.18 (our arithmetic: $76,393.44 × 50% × 0.25). That's an illustration of the formula, not a bill. The city says payment can be deferred to the final building inspection, and the full balance must be paid before a certificate of occupancy is issued.

Sources: City of Sierra Madre, Notice of Changes – ADU Public Facilities Fees (effective July 1, 2026, PDF)

12 · Help with fees

Fee waivers and help with fees

HCD's Handbook notes that some local agencies are creating funding programs for ADUs or waiving fees. Some local ADU loan programs also cover fees: Long Beach's Backyard Builders program, for example, lists building permits and other public agency fees as costs its loan can pay for. See our page on ADU financing in California.

Sources: HCD ADU Handbook (March 2026, PDF) · City of Long Beach, Backyard Builders Program

How to find out what you'll owe

Ask the agencies that actually charge the fees. State law sets the limits; the amounts come from them.

Measure your planned ADU's interior livable space. The 750 sq ft (impact fees) and 500 sq ft (school fees) lines are based on it.
Ask your city or county permit counter for its ADU fee list, including permit, plan check, inspection, and any impact fees, and whether a fee figure is available before you apply.
Ask your water and sewer providers whether they'll require a separate connection and how they calculate the fee.
Ask your school district (or districts) whether they charge fees on ADUs and at what rate per square foot.
Ask about standard plans, fee reductions, and fee deferral to final inspection.
If a fee seems to conflict with state law, ask the agency what law it's relying on. HCD's ADU page has resources and a portal for questions about local ADU rules.
City fees are separate from what you pay a builder. When you hire someone, see how to get ADU contractor bids, including the written-contract and down-payment rules.

Sources: Cal. Gov. Code §66311.5 (ADU and JADU fees) · HCD, Accessory Dwelling Units page

Quick answers

Are there impact fees for ADUs in California?

Not for an ADU with 750 square feet of interior livable space or less, or a JADU with 500 square feet or less (Gov. Code §66311.5(c)). An ADU over 750 square feet can be charged impact fees, but only in proportion to the size of the main home.

Is the ADU impact fee rule in Gov. Code 66324 or 66311.5?

As of January 1, 2026, it's §66311.5. SB 543 (2025) renumbered §66324 to §66311.5. Before March 2024 the same rules were in §65852.2(f).

How much does an ADU permit cost in California?

It depends on the city. Chula Vista's fee bulletin, for example, lists a total building permit fee of $3,951 for a detached ADU using a standard plan, and $1,604 for the first 400 square feet of a garage conversion, not counting impact, school, or utility fees. Ask your city for its current fee list.

Do I have to pay school fees on my ADU?

If your ADU has 500 square feet or more of interior livable space, your school district may charge them. ADUs and JADUs under 500 square feet aren't charged. The statewide Level I maximum is $5.38 per square foot as of January 28, 2026.

Do I have to pay water and sewer connection fees for an ADU?

For an ADU or JADU created inside existing space (Gov. Code §66323(a)(1)), the agency generally can't require a new connection or charge a related fee. For other ADUs, a separate connection may be required, with a fee proportionate to the ADU's burden and no more than the reasonable cost of service.

What are ADU fees in Pasadena?

Pasadena exempts ADUs of 900 square feet or less on single-family sites from its Residential Impact Fee and reduces some permit fees. ADUs with a Housing Agreement or built from a city Standard Plan get 50% off plan check fees. See the City of Pasadena's ADU page for details.

What does an ADU permit cost in San Diego?

We didn't find a single ADU permit fee figure from the City of San Diego. The city says ADUs under 750 sq ft and the first two ADUs on a property are exempt from its development impact fees, while school fees and the General Plan Maintenance Fee apply. The city's Information Bulletin 501 and fees page list its fees.

Sources

The statutes, bill texts, state guidance, and city fee schedules this page is based on.

Check ADU rules for your address