Statistics
ADU fee statistics
44 of 78 figures are HyreADU calculations. What the statute bars, what it lets a city charge proportionately, and what four published municipal schedules actually put on the invoice — with the arithmetic separated from the text on every row.
Written by HyreADU Research Desk Primary-source research and data analysis
Audited by HyreADU Research Desk Statutory citation and provenance-class audit
How to use this page
Below 750 square feet of interior livable space, a California ADU pays no impact fee at all — to anybody. Government Code § 66311.5(c)(1) bars a local agency, special district or water corporation from imposing “any impact fee” on an ADU of 750 square feet of interior livable space or less, or a JADU of 500 square feet or less.
Three classes of body are bound, and the word is “any”: a prohibition on the category, not a cap.
One square foot over, and the whole schedule arrives on a formula. Above 750 square feet, impact fees “shall be charged proportionately in relation to the square footage of the primary dwelling unit.” Behind a 2,000 square foot house that is about 38% at 751 square feet and 60% at 1,200; behind a 3,000 square foot house, 25% and 40%.
Those percentages are HyreADU arithmetic on a principle the statute states without writing out, and they move with your house, not your city. The cliff is visible in the one municipal worksheet that prints it. Sacramento’s CDD-0419 estimates about $5,271.90 in fees at 749 square feet and about $10,624.40 at 750: a step of $5,352.50 for one square foot, because park, SAFCA and Sacramento Transportation Authority charges are zero on the left of the line and live on the right.
“Impact fee” is narrower than “fees,” and a sub-750 unit is not free. Plan check and building permit fees are cost recovery and are not covered by the bar.
School developer fees run on a different statute with a 500-square-foot assessable-space test, and connection fees and capacity charges are excluded from the definition outright. 44 of 78 figures on this page are HyreADU calculations (44 hyreadu calculation, 34 agency published).
There is no priced per-city fee census on this site — the fee study publishes the retrieval log that explains why. Not legal or financial advice.
Read the provenance, not just the number
Fee pages on the open web are the worst-sourced genre in the ADU category, because a fee number that is undated and unattributed is indistinguishable from a fee number that is simply wrong.
A city adopts a schedule by resolution, revises it, and the figure that was right in 2022 is quoted forever. So this digest labels every figure, and refuses to print a dollar amount that cannot be traced to an adopted schedule or a statute.
Agency published — the Legislative Counsel’s text of the Government Code and Education Code, and a named municipal fee schedule with its revision date.
We cite the section and the form number, never a summary of them.
HyreADU calculation — the proportionality ratios, the San Francisco valuation-band arithmetic, the San José band totals, the Sacramento step, and every share of a construction median.
Where we added a city’s published cells together, the cells are named so the addition can be checked.
What is deliberately absent is a per-city priced fee table. The fee study attempted one and could not build it: every municipal site attempted returned HTTP 403 to automated retrieval, the platform hosting most California municipal codes returned 403 on every attempt, and the state housing department returned 403 with a scheduled-maintenance notice.
That page publishes the retrieval log rather than filling the gap with figures from commercial sources. This digest inherits that discipline.
A fee figure you cannot trace to an adopted schedule with a date is worse than no figure.
The municipal cells that do appear here are the ones the cost study retrieved directly from four published schedules — San Francisco, San José, Sacramento and Oakland. Four schedules are four schedules. A fifth city can look nothing like them, which is exactly why no statewide fee average appears anywhere on this site.
The figures most worth knowing
The proportion depends on your house, not on your city. Substitute your own primary dwelling size before using any percentage on this page.
Which fees may be charged on an ADU at all
Before any dollar figure means anything, the category question has to be settled: may this fee lawfully be charged on this unit? Every row below is quoted from the statutory text as retrieved on 2026-09-05, with the enactment line so the currency is visible.
Note that the fee section has been renumbered twice since 2024 — it was Government Code § 65852.2(f) until March 2024, then § 66324, and has been § 66311.5 since 1 January 2026.
| Fee type | May it be charged? | Authority | Class |
|---|---|---|---|
| Impact fee — ADU of 750 sq ft or less | No. Prohibited outright. | Gov. Code § 66311.5(c)(1). Binds a local agency, a special district and a water corporation alike. | Agency published |
| Impact fee — JADU of 500 sq ft or less | No. Prohibited outright. | Same sentence. A junior ADU is defined at § 66313(d) as no more than 500 sq ft, so every compliant JADU sits inside the bar. | Agency published |
| Impact fee — ADU over 750 sq ft | Yes, proportionately only. | “Charged proportionately in relation to the square footage of the primary dwelling unit.” Gov. Code § 66311.5(c)(1). | Agency published |
| Utility connection fee or capacity charge | Generally no — the unit is not a new residential use. | Gov. Code § 66311.5(b), unless the unit was constructed with a new single-family dwelling. | Agency published |
| A required new or separate utility connection | Generally may not be required. | Gov. Code § 66311.5(d), same exception. | Agency published |
| Connection or capacity charge where it is lawfully charged | Yes, capped at cost. | “Fees or charges shall not exceed the estimated reasonable cost of providing the service.” Gov. Code § 66013. | Agency published |
| School facilities fee | Only above an assessable-space threshold. | Levied “only if the resulting increase in assessable space exceeds 500 square feet.” Ed. Code § 17620(a)(1)(C)(i). A different measure from interior livable space. | Agency published |
| Any fee, on legalizing a pre-2020 unpermitted unit | No impact fees, no connection or capacity charges. | Gov. Code § 66311.7(e), with a narrow exception where utility infrastructure is required for Health and Safety Code § 17920.3 compliance. | Agency published |
| Plan check and building permit fees | Yes, as cost recovery. | Not reached by the ADU-specific bar. § 66311.5(a) routes ADU fees to the Mitigation Fee Act framework, under which these are cost recovery for the review itself. | Agency published |
California Government Code and Education Code as retrieved from leginfo.legislature.ca.gov on 2026-09-05. Full quotations and enactment lines on the fee study.
“Impact fee” is a narrower term than “fees,” and the confusion is expensive in both directions. A homeowner who believes a sub-750 unit is fee-free is surprised by the plan-check invoice. A homeowner who believes every charge is unavoidable pays an impact fee the statute prohibits.
Fee software and printed schedules do not always reflect the current statute, and the section number has changed twice — a line item challenged as “§ 65852.2(f)” is being challenged under a repealed numbering.
The proportionality formula, worked four ways
The proportionality arithmetic below is the most consequential in ADU project design, and it is ours, not the statute’s. The section states that impact fees above the threshold are “charged proportionately in relation to the square footage of the primary dwelling unit” and stops there — it does not write out the calculation.
The ratio of ADU floor area to primary dwelling floor area is the natural reading and the one every source we found uses. We apply it and we label it.
An agency construing the principle differently is not obviously wrong on the face of the section.
| ADU interior livable space | Impact fee permitted? | Behind a 1,500 sq ft house | Behind a 2,000 sq ft house | Behind a 2,500 sq ft house | Behind a 3,000 sq ft house | Class |
|---|---|---|---|---|---|---|
| 500 sq ft | No — prohibited | 0% | 0% | 0% | 0% | Agency published |
| 700 sq ft | No — prohibited | 0% | 0% | 0% | 0% | Agency published |
| 750 sq ft | No — prohibited | 0% | 0% | 0% | 0% | Agency published |
| 751 sq ft (the first chargeable square foot) | Yes, proportionately | 50% | 38% | 30% | 25% | HyreADU calculation |
| 800 sq ft | Yes, proportionately | 53% | 40% | 32% | 27% | HyreADU calculation |
| 900 sq ft | Yes, proportionately | 60% | 45% | 36% | 30% | HyreADU calculation |
| 1,000 sq ft | Yes, proportionately | 67% | 50% | 40% | 33% | HyreADU calculation |
| 1,200 sq ft | Yes, proportionately | 80% | 60% | 48% | 40% | HyreADU calculation |
Impact-fee proportion by ADU size against four illustrative primary dwelling sizes. HyreADU calculation applying the § 66311.5(c)(1) proportionality principle as retrieved on 2026-09-05. These are shares, not dollars, and not quotations from any adopted schedule.
Two cautions that decide whether this table is useful or misleading. First, the percentage is not a dollar. The amount depends on the underlying adopted schedule — parks, traffic, sewer capacity, school facilities — and in high-fee jurisdictions those schedules run to five figures per dwelling.
Second, the percentage moves with your house: the same 900 square foot unit is 60% behind a 1,500 square foot house and 30% behind a 3,000 square foot one, which is a factor of two on identical drawings.
The cliff in a real municipal worksheet
Sacramento is the rare California jurisdiction that publishes the threshold as three worked columns rather than as a sentence. The city’s form CDD-0419 estimates the fee stack on a new-construction ADU at 749, 750 and 1,200 square feet.
Park, SAFCA and Sacramento Transportation Authority charges are exactly zero in the first column and live in the second. The totals are the city’s. The steps and ratios between them are ours.
| Size on the worksheet | Declared valuation used | Park fee | SAFCA | STA mitigation | Total, excluding school | Class of the total |
|---|---|---|---|---|---|---|
| 749 sq ft | $127,929.20 | $0 | $0 | $0 | $5,271.90 | Agency published |
| 750 sq ft | $128,100.00 | $2,617.50 | $1,575.00 | $1,154.64 | $10,624.40 | Agency published |
| 1,200 sq ft | $204,960.00 | $2,617.50 | $1,575.00 | $1,154.64 | $14,842.50 | Agency published |
| The step from 749 to 750 sq ft | +$170.80 | +$2,617.50 | +$1,575.00 | +$1,154.64 | +$5,352.50 (2.02×) | HyreADU calculation |
City of Sacramento form CDD-0419, Accessory Dwelling Unit Fee Estimate (New Construction), revised 12 July 2026, retrieved 2026-09-05. The three column totals are the city’s own. The step row is HyreADU arithmetic on those totals. School developer fees are paid at the district and are not in any of these totals.
What this is and is not. It is one city’s published illustration of a statute every California city has to administer, and it is the clearest available evidence of the cliff’s magnitude.
It is not a HyreADU finding about every jurisdiction: the three fees that arrive at 750 square feet — $5,347.14 between them — are Sacramento’s park, flood-control and transportation schedules, and a different city has different ones or none.
To put that step in proportion, $5,352.50 is about 2.3% of the $230,351 indexed statewide construction median on the cost study — a fee movement worth more than the two square feet of construction it is attached to.
Where the fee is charged on floor area instead
San José departs from the California norm and prices ADU building fees by floor area rather than by declared valuation.
That makes the schedule unusually legible: three cells per size band, and a step at the same 750-square-foot line the impact-fee statute uses. Modular units get a 10 per cent lower plan review and a 20 per cent lower inspection.
Hourly floors of $325 for plan review and $315 for inspection apply if greater.
| Size band | Permit issuance | Plan review | Inspection | Building Division total | Class of the total |
|---|---|---|---|---|---|
| 0–750 sq ft | $422 | $1,137 | $1,732 | $3,291 | HyreADU calculation |
| 751–1,200 sq ft | $633 | $1,950 | $2,520 | $5,103 | HyreADU calculation |
| The step between the bands | +$211 | +$813 | +$788 | +$1,812 | HyreADU calculation |
City of San José Building and Structure Permits Fee Schedule, effective 10 August 2026, retrieved 2026-09-05. The individual cells are the city’s. The totals and the step are HyreADU addition and subtraction of those cells. Permit issuance includes addressing; inspection includes meter release.
The Building Division total is not the invoice. Public Works and utility-permit schedules are separate documents on separate effective dates, and school and parkland impact fees sit outside the Building Division entirely — the city’s own ADU fees page states that both “do not apply to ADUs less than 750 sq. ft.” The $3,291 figure for a sub-750 unit is about 1.4% of the indexed statewide construction median.
That is the honest scale of a building-permit fee on a small ADU in one large California city: real money, and not the number that decides the project.
Where the fee is charged on declared valuation
Most California fee schedules run on declared valuation, which means the fee is a function of a number the applicant writes on the application.
San Francisco publishes the band cleanly enough to work: for a total valuation of $50,001 to $200,000, plan review is $1,617 for the first $50,000 plus $15.60 per additional $1,000, and issuance is $677 plus $4.83 per additional $1,000.
Every additional $1,000 of declared valuation therefore adds $20.43. The valuations below are drawn from round figures and from the declared-valuation distribution on San Francisco’s own ADU permits.
| Declared valuation | Plan review | Permit issuance | Total | As a share of valuation | Class | Why this valuation |
|---|---|---|---|---|---|---|
| $75,000 | $2,007.00 | $797.75 | $2,804.75 | 3.7% | HyreADU calculation | Round figure inside the published band |
| $83,625 | $2,141.55 | $839.41 | $2,980.96 | 3.6% | HyreADU calculation | 25th percentile of declared valuation on San Francisco ADU permits (n = 1,314) |
| $100,000 | $2,397.00 | $918.50 | $3,315.50 | 3.3% | HyreADU calculation | Round figure inside the published band |
| $150,000 | $3,177.00 | $1,160.00 | $4,337.00 | 2.9% | HyreADU calculation | Median declared valuation on San Francisco ADU permits |
| $175,000 | $3,567.00 | $1,280.75 | $4,847.75 | 2.8% | HyreADU calculation | Round figure inside the published band |
| $200,000 | $3,957.00 | $1,401.50 | $5,358.50 | 2.7% | HyreADU calculation | Top of the published band |
HyreADU arithmetic on San Francisco Department of Building Inspection Table 1A-A, fees on and after 12 July 2026, retrieved 2026-09-05. The band structure and the two rates are DBI’s; the totals are ours. Declared-valuation percentiles are a HyreADU calculation on a San Francisco permit harvest generated 30 August 2026 (n = 1,314).
Three limits on this table, all of them material. First, DBI’s own Note 1 says these fees exclude Public Works, Planning, Fire and Public Health charges and the separate plumbing, electrical and mechanical permits — this is a fraction of the building-department invoice, not the invoice.
Second, the arithmetic is confined to the published $50,001–$200,000 band; San Francisco’s 75th percentile declared valuation of $250,000 falls outside it, and we did not retrieve the next band, so we compute nothing there.
Third, and structurally: a fee computed from declared valuation gives the applicant a direct financial reason to declare a low number, which is precisely the bias the permit-valuation digest measures.
School developer fees run on a different statute entirely
School developer fees are the most commonly conflated line on an ADU fee estimate.
School facilities fees are levied by the school district under Education Code § 17620, not by the city under the Mitigation Fee Act, and the threshold is a different number on a different measure: the levy applies “only if the resulting increase in assessable space exceeds 500 square feet.” A 700-square-foot ADU can therefore sit safely inside the impact-fee bar and squarely outside the school-fee threshold at the same time. The rates below are published; the products are illustrations.
| District rate as published | At 600 sq ft | At 800 sq ft | At 1,000 sq ft | At 1,200 sq ft | Class of the products | Source of the rate |
|---|---|---|---|---|---|---|
| Sacramento City Unified — $5.38/sf | $3,228 | $4,304 | $5,380 | $6,456 | HyreADU calculation | City of Sacramento form CDD-0226, revised 1 September 2026 |
| San Juan Unified — $5.38/sf | $3,228 | $4,304 | $5,380 | $6,456 | HyreADU calculation | City of Sacramento form CDD-0226, revised 1 September 2026 |
| Elk Grove Unified — $7.23/sf | $4,338 | $5,784 | $7,230 | $8,676 | HyreADU calculation | City of Sacramento form CDD-0226, revised 1 September 2026 |
| Oakland Unified (as listed by the City of Oakland) — $5.17/sf | $3,102 | $4,136 | $5,170 | $6,204 | HyreADU calculation | City of Oakland Impact Fee Amounts page, retrieved 2026-09-05 |
District rates as published on the pages named, retrieved 2026-09-05. The dollar products are HyreADU arithmetic: a published rate multiplied by a stated floor area.
They are not what any district will bill. Assessable space is the district’s measurement against your plan set, not a number from this page, and § 66311.5(c)(3) treats an ADU or JADU under 500 square feet of interior livable space as not increasing assessable space by 500 square feet.
Two of the rates above are the State Allocation Board Level 1 residential rate of $5.38 per square foot as listed on Sacramento’s district roster of 1 September 2026; Elk Grove Unified is listed higher at $7.23.
Oakland’s Impact Fee Amounts page still listed $5.17 residential on the retrieval date, and we report what the page said rather than silently updating it to the Level 1 figure — a district rate is adopted, not inferred.
Proof of payment at the district is typically required before a city will issue the permit, and the charge is not in the city’s own worksheet total.
How to get the number that applies to your parcel
No page can price your fee stack, and one that offers to is guessing. What a page can do is name the documents that govern, in the order that produces a defensible answer. Steps two and three rest on statutory publication duties, so they are requests the agency is obliged to meet.
- 1 Fix the interior livable space figure, and get the measurement basis agreed in writing
Everything downstream turns on whether the unit is at or below 750 square feet of interior livable space.
Government Code § 66313(e) defines livable space as “a space in a dwelling intended for human habitation, including living, sleeping, eating, cooking, or sanitation” — which is not gross floor area, and not necessarily the measure the building department uses elsewhere on the same plan set.
A project drawn to 748 square feet on one measure and assessed at 762 on another has lost the exemption on a drafting convention.
- 2 Ask for the adopted schedule and the resolution number that adopted it
Not the handout and not the online estimator — the adopted schedule, with the ordinance or resolution number and the adoption date.
Government Code § 66016 required the underlying cost data to be publicly available at least ten days before the adopting meeting, so ask for that too. That is the document worth putting in a project budget.
- 3 Ask the water and sewer providers separately, because they are separately bound
Section 66311.5 binds “a local agency, special district, or water corporation.” Your water or sewer service may come from a district that is not the city and that runs its own schedule.
Quote § 66311.5(b) to that district in writing, by its current number, and ask for its § 66013 reasonable-cost basis if a charge is proposed.
- 4 Ask the school district whether the assessable-space threshold is exceeded
A separate statute, a separate body and a separate threshold. Education Code § 17620(a)(1)(C)(i) levies only where the increase in assessable space exceeds 500 square feet. Get the district’s current adopted rate and its measurement of your plan set — not a rate from a city roster, and not one from this page.
- 5 Check the invoice line by line, and cite the current section number
This is the step that recovers money. If a line item is an impact fee on a unit of 750 square feet or less of interior livable space, or a capacity charge on a unit not built with a new single-family dwelling, § 66311.5 is the answer — and it must be cited as § 66311.5, not as § 66324 and certainly not as § 65852.2(f).
Both of those numberings appear in permit software and printed schedules still in use.
- 6 If you are legalizing an existing unit, invoke § 66311.7(e) explicitly
A unit constructed before 1 January 2020 carries its own waiver: no impact fees and no connection or capacity charges, with a narrow exception where utility infrastructure is required to comply with Health and Safety Code § 17920.3.
It is a different provision from the size-based bar, it is easy for a counter to miss, and it is set out on the legalization study.
Figures we will not repeat
- An “average California ADU permit fee”
California has roughly 480 cities and counties, each adopting its own schedule under the Mitigation Fee Act, plus school districts and water and sewer districts with their own.
There is no 480-row table behind any average in circulation, including ours — because we do not have one.
Inside the four schedules on this page, a sub-750 square foot building-fee total ranges from $3,291 in San José to about $5,271.90 in Sacramento to a San Francisco figure that depends entirely on the declared valuation. That is four cities, not a distribution.
- A dollar impact fee attached to the 750 square foot threshold
The statute removes a category; it does not name a price. What crossing the line costs depends on the adopted park, traffic, sewer-capacity and school schedules of one specific agency, and on the size of your primary dwelling.
The percentages on this page are shares of an unknown, and any dollar figure we published for “the cost of going over 750” would be an invention dressed as a statistic. Sacramento’s worksheet is one city’s number, labeled as one city’s number.
- “Sub-750 ADUs are exempt from fees”
They are exempt from one category — impact fees — and that category, though usually the largest, is not the whole invoice. Plan check and building permit fees are cost recovery and survive the bar.
School fees run on Education Code § 17620 with a 500-square-foot assessable-space test. The physical utility work required to serve a unit is not an impact fee. San José’s $3,291 Building Division total is charged on a unit the impact-fee statute fully protects.
- The proportionality percentage quoted without a house size
“Thirty-eight per cent at 751 square feet” is only true behind a 2,000 square foot primary dwelling.
Behind a 1,500 square foot house it is 50%; behind a 3,000 square foot house it is 25%.
Every percentage on this page carries the primary dwelling size it was computed against, and any figure quoted without one has lost half the formula.
- A fee cited to § 65852.2(f) or § 66324
Both are repealed numberings. SB 477 recodified ADU law out of § 65852.2 into §§ 66310–66342 effective 25 March 2024, and SB 543 renumbered the fee section from § 66324 to § 66311.5 effective 1 January 2026.
A great deal of published guidance — including some still on agency sites — cites the old numbers. Citing the current one is what makes a fee challenge legible at the counter.
The finding underneath all of these figures
The statutory half of ADU fees is unusually clear, and the priced half is, at scale, unreadable. Every provision quoted on this page came back cleanly from the Legislative Counsel’s code service on the first request.
Not one municipal fee schedule did. The fee study logged the attempts: every city planning and building fee page attempted returned HTTP 403 to automated retrieval; library.municode.com, which hosts most California municipal codes, returned 403 on every attempt and its mirrors timed out; and hcd.ca.gov returned 403 with a scheduled-maintenance notice for an entire session.
We want to state the inference carefully. A 403 to an automated client is not evidence that an agency is concealing anything, and in most cases these documents are perfectly available to a person with a browser.
The four schedules quoted on this page were retrieved by exactly that route on the cost study. The point is not concealment. The point is scale.
Government Code § 66016 requires an agency, before adopting or increasing a fee, to make available “data indicating the amount of cost, or estimated cost, required to provide the service” at least ten days before the meeting.
Government Code § 66013 requires connection-fee and capacity-charge information to be made available within 180 days after each fiscal year. Those are duties to publish.
A publication regime that is legible to one person opening one PDF, and illegible to any process that would compare 480 of them, satisfies the letter and defeats the purpose.
HyreADU analysis. The practical consequence is that the comparison California ADU applicants most need — what does this cost here, against what it costs one town over — does not exist anywhere, including on this site. That absence is not a gap in anyone’s method.
It is a structural feature of how fee data is published, and it is the reason a homeowner at the 750-square-foot boundary is making a five-figure decision on a percentage rather than on a number.
We would rather publish the shorter honest page, the arithmetic the statute forces, and the log of what could not be read, than a table of fee figures we cannot trace to an adopted schedule with a date.
Citing these figures
Link the fee study rather than this digest where you can: the full statutory quotations, the enactment lines and the retrieval log live there, and a fee figure that travels without its date is the failure mode this whole page is written against.
Where a figure is labeled HyreADU calculation, attribute it to HyreADU and say what it was computed from — “HyreADU arithmetic on the Government Code § 66311.5(c)(1) proportionality principle, against a 2,000 square foot primary dwelling,” or “HyreADU addition of San José Building Division fee cells effective 10 August 2026.” Where it is Agency published, cite the code section or the named municipal form with its revision date; we are repeating it.
Corrections are welcome and are published on the page with a dated note: hello@hyreadu.com. If you can supply an adopted ADU fee schedule with its resolution number and date — particularly from a jurisdiction not on this page — that is the single input that would most improve it.
Questions
Do I have to pay impact fees on an ADU in California?
What happens at exactly 751 square feet?
How much does the 750 square foot threshold actually cost in dollars?
Is a sub-750 square foot ADU free of all fees?
Do I have to pay a water or sewer connection fee for an ADU?
Are school fees charged on an ADU?
Do I pay fees to legalize an unpermitted ADU?
Why does this page not list fees city by city?
Which figures on this page are HyreADU’s own?
Written and audited by
HyreADU Research Desk
Primary-source research, data analysis and fact checking
We are a research desk, not a builder. We read the permit extract, the statute, the HCD return or the fee schedule ourselves, and publish each figure with its source and retrieval date.
Where a number cannot be traced to a primary source, we leave it out and say what we could not verify. Our store-based claims cover California only.
- CA
- the only state this desk will make store-based claims about
- 5
- jurisdictions with extracted ADU permit evidence
- 735
- CSLB-verified companies in the California store
- 0
- national claims from a one-state store
How this desk works
- Primary sources only. Permit counts come from the city or county that issued the permit. Production counts come from HCD’s Annual Progress Report. Rents come from HUD or the Census. We do not cite an article that cites a source; we download the source and compute the figure ourselves.
- This is a California site. The company store is 734 California firms and one New Mexico firm. Permit evidence exists for five named jurisdictions: Los Angeles, San Francisco, Sacramento, San José and unincorporated Marin. A number from that store is titled to those places, never to the United States.
- A permit is not a completion, and a license is not an ADU grade. California licenses no ADU classification. Being named on an ADU permit is evidence of engagement in that jurisdiction, not of quality, completion, or work anywhere else. Owner-builder permits are excluded from contractor counts.
- Calculation is labeled as calculation. Figures we derive are never presented as something HCD, HUD, the Census or a city published. Terner Center research is cited as Terner’s, never restated as ours.
- We do not design, permit or build ADUs, and we take no payment for placement, ranking or a favorable mention. Pages that look like rankings are not: they publish public-record counts and let the reader decide.
- Nothing here is legal, tax or financial advice. Zoning, underwriting and appraisal practice vary by jurisdiction, lender and appraiser. The useful next step on a specific lot is the planning counter and a licensed professional.
Data as of Government Code §§ 66311.5, 66311.7, 66013 and 66016 and Education Code § 17620 retrieved from leginfo.legislature.ca.gov 2026-09-05; municipal fee schedules for San Francisco, San José, Sacramento and Oakland retrieved 2026-09-05; San Francisco declared-valuation percentiles from a harvest generated 30 August 2026. Authorship on this site is organizational: the analysis belongs to the desk rather than to a named individual, and we do not publish credentials we do not hold.
Our editorial policy sets out how we source, date and correct what we publish.
Sources & retrieval dates
- California Government Code § 66311.5 — ADU fees, the 750 square foot impact-fee bar, and utility connection treatment , (c)(1): “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 or a junior accessory dwelling unit that has 500 square feet of interior livable space or less,” and “Any impact fees charged for an accessory dwelling unit that has more than 750 square feet of interior livable space shall be charged proportionately in relation to the square footage of the primary dwelling unit.” (b) and (d): connection fee, capacity charge and separate-connection treatment. (a): routes ADU fees to the Mitigation Fee Act. Enactment line: “Added by renumbering Section 66324 by Stats. 2025, Ch. 520, Sec. 7. (SB 543) Effective January 1, 2026.” Retrieved 2026-09-05.
- California Government Code § 66013 — connection fees and capacity charges limited to reasonable cost , “Fees or charges shall not exceed the estimated reasonable cost of providing the service” absent two-thirds voter approval. Defines capacity charge and connection fee separately, and requires charge information to be made available within 180 days after each fiscal year. Amended by Stats. 2020, Ch. 370, Sec. 180 (SB 1371). Retrieved 2026-09-05.
- California Government Code § 66016 — notice and cost data before adopting or increasing a fee , Notice mailed at least 14 days before the meeting; cost or estimated-cost data made available to the public at least 10 days before it; at least one open and public meeting. Cited here as the publication duty against which the fee study’s retrieval log should be read. Amended by Stats. 2006, Ch. 643, Sec. 19. Retrieved 2026-09-05.
- California Education Code § 17620 — school facilities fees and the 500 square foot assessable-space threshold , Subdivision (a)(1)(C)(i) applies fees to residential construction “only if the resulting increase in assessable space exceeds 500 square feet.” A different threshold, on a different measure, from the Government Code impact-fee bar. Amended by Stats. 2010, Ch. 541, Sec. 1 (AB 2048). Retrieved 2026-09-05.
- California Government Code § 66311.7 — no impact fees or connection charges when legalizing a pre-2020 unit , Subdivision (e): the homeowner “shall not be required to pay impact fees or connection or capacity charges except when utility infrastructure is required to comply with Section 17920.3 of the Health and Safety Code and when the fee is authorized by subdivision (e) of Section 66311.5.” Added by renumbering § 66332 by Stats. 2025, Ch. 520, Sec. 9 (SB 543). Retrieved 2026-09-05.
- California Government Code § 66313 — definitions of livable space and junior accessory dwelling unit , Subdivision (e): livable space is “a space in a dwelling intended for human habitation, including living, sleeping, eating, cooking, or sanitation” — the measure in which the 750 and 500 square foot thresholds are expressed. Subdivision (d): a JADU is no more than 500 square feet of interior livable space, contained entirely within a single-family residence. Retrieved 2026-09-05.
- City of Sacramento — CDD-0419 Accessory Dwelling Unit Fee Estimate (New Construction), revised 12 July 2026 , Worked columns at 749, 750 and 1,200 square feet, on declared valuations of $127,929.20, $128,100.00 and $204,960.00. Totals excluding school fees of about $5,271.90, $10,624.40 and $14,842.50. Park ($2,617.50), SAFCA ($1,575.00) and STA mitigation ($1,154.64) are zero in the 749 column and live in the other two. Retrieved 2026-09-05.
- City of Sacramento — CDD-0245 residential fee table and CDD-0226 school district impact fees , CDD-0245 (revised 12 July 2026): new living area valued at $170.80 per square foot; garage conversion at $101.16. CDD-0226 (revised 1 September 2026): Sacramento City Unified $5.38 per square foot residential; San Juan Unified $5.38; Elk Grove Unified $7.23, paid at the district with proof required before city issuance. Retrieved 2026-09-05.
- City of San José — Building and Structure Permits Fee Schedule (10 August 2026) and Fees for ADUs page , ADU fees charged by floor area: 0–750 sq ft issuance $422, plan review $1,137, inspection $1,732; 751–1,200 sq ft $633 / $1,950 / $2,520. Modular units get 10 per cent lower plan review and 20 per cent lower inspection. Hourly floors $325 (plan review) and $315 (inspection). The city’s ADU page states that school and parkland impact fees “do not apply to ADUs less than 750 sq. ft.” Retrieved 2026-09-05.
- San Francisco Department of Building Inspection — Table 1A-A, building permit fees on and after 12 July 2026 (Ord. 112-26) , Valuation band $50,001–$200,000: plan review $1,617 for the first $50,000 plus $15.60 per additional $1,000; issuance $677 plus $4.83 per additional $1,000. Note 1: these fees exclude Public Works, Planning, Fire and Public Health charges and the separate plumbing, electrical and mechanical permits. Retrieved 2026-09-05.
- City of Oakland — Impact Fee Amounts and Impact Fee Assessment and Appeal Information (Ord. 13853, effective 13 September 2025) , ADUs listed as exempt from the city’s Affordable Housing, Transportation and Capital Improvements impact fees, in addition to the statewide bar. School fees on the Amounts page listed at $5.17 per square foot residential as retrieved. Building permit fees described by the city itself as “usually 4–6% of project value.” Retrieved 2026-09-05.
- HyreADU San Francisco ADU permit harvest , Generated 30 August 2026 from the San Francisco Department of Building Inspection open-data extract (i98e-djp9), joined to Building Permits Contacts (3pee-9qhc). Issued permits only; owner-builder-named records excluded. n = 1,314 with a declared valuation above zero; p25 $83,625, median $150,000, p75 $250,000. Declared valuation, not construction cost. Retrieved 2026-08-30.
Know which side of 750 square feet you are on
Below the line, no impact fee may be imposed — not by the city, not by a special district, not by a water corporation. Above it, a proportional share of the whole schedule attaches. Fix the interior livable space figure and get the measurement basis agreed before the plan set is final.
HyreADU does not design, permit or build accessory dwelling units, does not practice law and does not provide financial advice. This page is informational and is not legal, tax or financial advice.
It describes California statutory text as retrieved on 5 September 2026 and municipal fee cells from four named schedules with their revision dates; it contains no fee figure for any jurisdiction not named on it, because no comprehensive municipal fee census could be retrieved.
Percentages are HyreADU arithmetic applying the statutory proportionality principle against an illustrative primary dwelling size stated with every figure; they are shares, not dollars, and not quotations from any adopted schedule.
The statute states the proportionality principle without writing out the calculation, and an agency may construe it differently.
School-fee products are a published district rate multiplied by a stated floor area and are not what any district will bill; assessable space is the district’s measurement. Fees are set by individual agencies and vary widely between neighboring jurisdictions.
The useful next step is the adopted fee schedule with its resolution number, requested in writing, from the city and from each water, sewer and school district separately.