Methodology

Where the fee data comes from

Fee information is published at one of two evidence levels. Our industry experience helps us organize the questions, but it does not turn an unsupported number into an official city rate:

• Published sources. City fee schedules, ADU pages, and permit portals. A source link appears when the page supports the displayed fee or process statement.
• Working estimates. Where a city publishes no usable line item, we show an early-planning assumption and label it as unverified. It must not be treated as the city’s rate.

Reference sizes

We precompute fee estimates at fixed reference sizes so every city can be compared on the same basis: 400 sq ft, 500 sq ft, 749 sq ft, 750 sq ft, 751 sq ft, 1000 sq ft, 1200 sq ft.

The 749 / 750 / 751 trio exists because of a California state-law threshold: ADUs under 750 sq ft are generally exempt from development impact fees, while larger ADUs may be charged impact fees proportional to the primary dwelling. Comparing 749 and 751 sq ft side by side shows how much that threshold can matter for your project.

What the estimate does and does not include

Estimates aim to cover permit-related fees:

• Building permit fees
• Plan check fees
• Development impact fees
• School district fees
• Utility connection charges
• Inspection fees
• Technology and records surcharges

Estimates exclude construction cost, architectural or design fees, and financing costs. Those typically dwarf permit fees and vary far more by contractor, materials, and finishes than by city.

How to verify with your city

Before you finalize a budget, call or visit the building department for your city and:

• Ask for the current fee schedule that applies to ADUs.
• Ask whether development impact fees apply at your specific square footage.
• Get the fee estimate in writing before you commit to a budget.

Permit process guides

Where available, permit process guides are summarized from official city pages to explain where to apply, what to prepare, and how the review typically proceeds. Not every city has a guide yet — where one is missing, we say so rather than guessing at a process we have not verified.

Corrections and known limits

We would rather be candid about the gaps than smooth them over:

• Some cities have no itemized fee data collected yet.
• Some cities’ totals do not change across reference sizes, so the size selector will not move the estimate for those cities.
• Some source values are duplicated in our data, which can inflate category totals for a small number of cities.
• A few stored totals fall outside any plausible range for a single ADU; we hold those back rather than publish a number we know is wrong.

Who prepares this

This site is prepared by GetYourPermit editorial team. Read more about the project on the about page, or email hello@getyourpermit.app if you spot a number that looks wrong.