All About ADU Permit Fees & Waivers

California law exempts qualifying accessory dwelling units (ADUs) 750 square feet or less from covered impact fees, but it does not waive every project charge. Larger units may face additional impact fees, depending on applicable law. Your budget should separately account for potential sewer connection charges, school fees, and plan review and building permit fees.

Some municipalities offer additional ADU fee waivers or reductions, subject to local eligibility requirements. These programs may help homeowners reduce construction costs, but availability and potential savings require confirmation with the permitting authority. Understanding ADU permit costs helps you budget accurately. Read on to learn how permit fees work, what SB13 addresses, and how to investigate additional savings for your property.

Impact-fee threshold note: Under the March 2026 California HCD ADU Handbook, the statewide development-impact-fee exemption includes ADUs with 750 sq ft of interior livable space or less. Above 750 sq ft, applicable impact fees must be proportional. School, utility, plan-check and permit charges follow separate rules.

Do I need a permit to build an ADU in California?

Yes, you need a building permit for an accessory dwelling unit. Requirements vary by jurisdiction, so confirm the process with your local building department. You can also read more about each city’s ADU regulations.

How much does an ADU permit cost?

For an accurate estimate of ADU permits and fees, request a project-specific breakdown from the jurisdiction where your property is located. Include plan review, school fees, building permits, and any applicable impact fees for your proposed unit. Treat sewer and water upgrades as separate budget items, since existing service capacity and connection requirements can substantially affect the total.

TABLE: ADU Permit Fees per Square Foot by City - Los Angeles

Confirm current charges with the permitting jurisdiction. Budget separately for sewer and water fees; do not treat estimates as official quotes.

How much does an ADU permit cost in Los Angeles?

To estimate ADU permit costs in Los Angeles, use the City of Los Angeles below as a starting point and request a current fee breakdown from the city. Confirm when plan review, permit, and impact fees become payable, since payment deadlines depend on the fee category and applicable requirements.

Reference: City of Los Angeles fee schedules. Verify current rates, applicability, and effective dates with the responsible authority.

Water and sewer capacity charges in Los Angeles

For a property in the City of Los Angeles, confirm water service requirements with the Los Angeles Department of Water and Power. Properties in Diamond Bar or Pomona may have different providers. Ask whether your ADU requires a new meter, a larger meter, or service upgrades, and request an itemized estimate. Meter size, existing service capacity, and provider rules determine the applicable charges. Check the following:

• Whether the existing meter and service can support the ADU.
• Whether a new or larger meter triggers installation or capacity charges.
• Whether the provider offers credit for existing service capacity.

When a larger meter replaces an existing one, ask whether the provider credits previously paid capacity charges. Do not assume you will pay only the difference; request a written calculation under the applicable rate schedule.

You can also consult City of Los Angeles’s Bulletin on Water and Sewer Fee Calculation and Los Angeles Water Authority’s Capacity Charges, then confirm their applicability with your service provider.

What fees do I have to pay when building my ADU?

ADU fees generally fall into three categories: plan review fees, building permit fees, and applicable impact fees. Utility and school charges may require separate budgeting. Here is what each category covers.

What is a plan check fee?

Plan review fees pay the permitting authority to evaluate your ADU plans for code compliance. They are separate from design, document preparation, and printing costs. Confirm whether your jurisdiction accepts electronic submissions or requires printed documents at any stage. Before relying on submission guidance associated with Carlsbad, Vista, Chula Vista, Los Angeles, Escondido, Poway, or Solana Beach, verify current requirements with the responsible building department. If paper copies are required, budget for printing, delivery, and any revised plan sets.

What is a building permit fee?

Building permit fees cover the authorization and administrative services associated with construction; plan review may be charged separately. These processes help the permitting authority verify compliance with applicable building and safety requirements. Do not apply a Los Angeles County fee schedule automatically to a property within an incorporated city. For Los Angeles, Diamond Bar, or Pomona, request the responsible building department’s current calculation, including valuation-based charges, inspection fees, and any applicable surcharges.

What is an impact fee?

An “impact fee” generally funds public facilities needed to serve new development. Not every charge associated with an ADU falls into this legal category, and exemptions differ by fee type. Distinguish impact fees from utility, school, and permitting charges when reviewing the following categories:

1. Sewer Fees: Sewer connection or capacity charges may help fund infrastructure needed to serve an additional dwelling. Ask the sewer agency whether your ADU qualifies for an exemption or requires a separate connection, and distinguish these charges from on-site plumbing work.
2. Water Fees: Water connection and capacity charges may apply when a project requires new or expanded service. Confirm meter requirements, service capacity, applicable exemptions, and infrastructure charges with the actual water provider rather than assuming citywide rules apply.
3. School Fees: School facility fees support eligible school construction or expansion. Their applicability follows separate legal requirements, including size-related exemptions. Request confirmation from the school district serving the property before including these charges in your budget.
4. Development Impact Fees: These fees fund eligible public facilities associated with growth, such as parks or transportation infrastructure. They are distinct from routine plan review and inspection charges. Confirm applicable exemptions, proportional calculations, and current fee schedules with the permitting jurisdiction.

Applicable charges vary by jurisdiction, service provider, project characteristics, and state-law exemptions, so obtain a property-specific fee estimate.

SB13: Waived Impact Fees for ADUs Under 750 SF

Passed in 2019, SB13 established California ADU provisions that include an exemption from covered impact fees for units under 750 square feet. This exemption does not eliminate all project charges. Review the March 2026 California ADU Handbook and applicable current law to determine which fees remain payable.

Local agencies must adopt and administer fees under applicable legal requirements, but not every fee schedule requires annual city council approval. A local waiver is an authorized reduction or exemption, not permission to disregard an adopted schedule. State law also limits covered impact fees for qualifying ADUs, including an exemption for units 750 square feet or less under the applicable rules. That threshold does not automatically exempt the project from plan review, building permits, school fees, or utility charges. Ask the responsible agency to identify each charge, its legal basis, and any exemption that applies to your proposed unit.

New for 2027: SB 1117’s Effect on Impact Fees

Before relying on a January 1, 2027 change attributed to SB 1117 (Cervantes), verify its enacted provisions, effective date, and applicable ADU impact-fee thresholds.

For a property with up to two ADUs, ask whether the rules applicable to your project calculate covered impact fees using only interior livable area above 750 square feet, proportionate to the primary home’s size. Under that approach, an 800-square-foot ADU would use 50 square feet rather than the full 800 square feet.

For properties with more than two ADUs, verify whether covered impact fees use the unit’s full area in a proportional calculation. Confirm how the applicable law treats units exactly 750 square feet, rather than assuming that “under 750” and “750 or less” are interchangeable.

An impact-fee exemption does not eliminate every development cost. Building permits, school fees, and utility connection or capacity charges follow separate rules and require individual review.

What are the requirements for an ADU permit fee waiver?

Beyond state-mandated exemptions, any additional city fee waiver or reduction may carry eligibility requirements. If a program is available, ask whether it requires occupancy by a family member, caregiver, or income-qualified tenant. Some programs may require a recorded agreement restricting occupancy or use of the property. Review those obligations before assuming the savings justify participation. Application costs can include document preparation, notarization, recording, and compliance reporting. Los Angeles, Diamond Bar, and Pomona are separate jurisdictions, so confirm program availability and conditions directly with the city responsible for your property.

What are the steps for getting an ADU permit fee waiver? Should I get my ADU plans done first?

The application process depends on the specific waiver program, if one is available. Request current forms and instructions from the responsible jurisdiction before preparing documents. Ask whether signatures require notarization, who records any agreement, and when approval occurs. Supporting documents may include a statement identifying the proposed occupant or evidence of household income, such as tax returns or pay stubs. Submit sensitive financial records only through the agency’s approved process, and confirm any ongoing certification requirements.

Ask whether a complete plan submission or active plan review is required before requesting a waiver. Some programs tie eligibility and fee calculations to a specific permit application, but procedures vary. If a waiver determines whether your project is financially feasible, contact the jurisdiction before committing to design or construction expenses. Request written clarification of available reductions, eligibility conditions, and application timing.

Once your permit is issued, confirm the deadlines for starting work and keeping it active, including inspection and extension requirements. We discuss these timing considerations in our guide to how long ADU permits last in Los Angeles..

What cities offer ADU permit fee waivers?

Check Encinitas,Vista, and La Mesa with the relevant jurisdiction to confirm whether any fee waiver applies to your project.

Encinitas ADU Fees & Waivers

For a Los Angeles, Diamond Bar, or Pomona project, verify impact, sewer, and school charges separately with the responsible agencies. A 600-square-foot ADU may qualify for a state impact-fee exemption while remaining subject to school fees or other charges under separate rules. Do not assume that an impact-fee exemption also eliminates sewer connection or capacity charges.

If the City Council considered Resolution No. 2026-34 references a May 20, 2026 adoption and July 20, 2026 effective date, verify the issuing jurisdiction, adopted fee study, and relevance to your property before relying on those dates.

When reviewing a local fee framework, confirm these ADU-specific requirements with the permitting authority:

• ADUs 750 sq ft or less: Confirm the applicable state exemption from covered development impact fees and verify the provisions referenced by AB 881.
• ADUs 750 sq ft or larger: Request the legally applicable proportional calculation, including any effective-date changes, rather than assuming a single-family per-square-foot rate automatically applies.

A revised fee schedule may change your project’s budget, but the effect depends on applicable exemptions and calculation rules. Review staff report and confirm its jurisdiction and current applicability.

Vista ADU Fees & Waivers

For an ADU at or above the applicable impact-fee threshold, ask your permitting jurisdiction whether it offers any additional waiver. Request an itemized list of potentially eligible charges, such as fire protection, parks, public facilities, or transportation fees. Do not assume a particular savings amount or universal eligibility. Before relying on a reduction, confirm whether the program imposes requirements such as the following:

• Whether the ADU must house an eligible household for a specified period after the certificate of occupancy is issued.

• Which household categories qualify, potentially including:

  • An income-qualified household, if the program uses a threshold such as 80% of area median income. Verify the current limits, household size, geographic area, and applicability of $119,500.
  • A family member or caregiver providing regular care to an eligible resident, if permitted.

• Whether the owner must execute and record an occupancy-restriction covenant, and who monitors compliance.

Consult your jurisdiction’s official ADU and fee-waiver guidance for application steps. Before completing Vista ADU Fee Waiver Program, confirm that the form applies to your property and the current program.

La Mesa ADU Fees & Waivers

Ask the relevant city whether ADU-only projects qualify for any park, transportation, or permitting-fee reduction. Obtain the current policy and eligibility requirements in writing rather than assuming a fixed dollar credit applies. Our La Mesa ADU Guide can help frame the questions to ask, but the responsible agency must confirm any available savings.

How will permit costs affect the cost of my build?

Fees can change under adopted schedules, and the amount due may depend on when an application is submitted, a permit is issued, or another payment trigger occurs. Request an early estimate and ask whether it remains valid through permitting. Confirm which charges your contractor includes and which you must pay directly. Covered impact fees may be subject to proportionality rules, but not every charge follows the same formula. When comparing a 750-square-foot ADU with an 800-square-foot design, verify the exact statutory threshold and applicable effective date before assuming either option qualifies for an exemption.

Permit fees and regulations are constantly changing

This article provides practical guidance for reviewing ADU fees, not a project-specific estimate or legal determination. Requirements can change as state laws, local fee schedules, and utility policies evolve. Use the March 2026 California ADU Handbook as a statewide starting point, then confirm current requirements with the agencies responsible for your property.

Uni Construction, a DBA of Orep Development Inc., license 1026926, aims to help homeowners understand ADU planning and budgeting. Min Kang is CEO. Contact the team to discuss your property’s needs, identify questions for the responsible agencies, and develop a project-specific scope. Confirm fees, approvals, and any rental restrictions with the relevant authorities before making financial commitments or relying on projected returns.