ADU Cost in Sacramento (2026): Permit Fees, Impact Fees and What Drives the Price

When Sacramento homeowners price an ADU, most of the attention goes to the build itself. The City fees, school fees and utility charges are smaller, but they are the part people get wrong, because the rules changed on January 1, 2026 and some of the City's own forms have not caught up. Here is what the numbers look like this year, where they come from, and which ones you can actually control.

The short answer

• Construction is roughly 80% of the total. The City's ADU Resource Center puts it plainly: about 80% of the budget goes to materials and labor, and about 20% to design, consulting and permits.
• City permit and impact fees on the City's own 2026 estimate range from about $5,300 (749 sq ft) to about $14,800 (1,200 sq ft), before school and sewer fees.
• School fees do not apply to ADUs under 500 sq ft; larger ADUs pay $2.90 to $7.23 per sq ft depending on the district.
• Size is the biggest fee lever. Stay at 750 sq ft or under and state law takes impact fees off the table; stay under 500 sq ft and school fees go too.

What the City of Sacramento charges in 2026

The City publishes an ADU fee estimate (form CDD-0419, revised July 12, 2026). It values new ADU construction at $170.80 per sq ft for permit purposes. That is a valuation used to calculate fees, not what it costs to build. Its three sample sizes:

ADU size	Permit valuation	City fees on the estimate
749 sq ft	$127,929	about $5,272
750 sq ft	$128,100	about $10,624
1,200 sq ft	$204,960	about $14,843

At 1,200 sq ft the estimate breaks down into a building permit ($1,790), plan review ($752), Park Development Impact Fee ($4,188), SAFCA flood-control fee ($2,520), STA mitigation fee ($1,416) and construction excise tax ($946). Regional sanitation and sewer fees are listed as "check with County", and school fees are paid separately at the school district.

Two City items are free or close to it: the optional ADU zoning review has had no fee since July 12, 2026 (it was $117), and the City's three Shelf Ready plan sets (367, 559 and 747 habitable sq ft) cost nothing to use.

The 750 sq ft rule changed this year

California Government Code section 66311.5 (renumbered from 66324 on January 1, 2026 by SB 543) says a local agency, special district or water corporation shall not impose any impact fee on an ADU with 750 square feet of interior livable space or less. Above 750 sq ft, impact fees must be charged proportionately to the size of the main house.

The old wording was "less than 750", which is why the City's estimate still jumps between 749 and 750 sq ft: at 750 sq ft the 2026 form still lists park, SAFCA and STA fees. Under the current statute a 750 sq ft ADU should owe none of them. If your plans land exactly on 750 sq ft, raise it at plan review rather than paying the higher column.

Note what the exemption does not cover: connection fees and capacity charges for water and sewer are a separate category, covered in the utilities section below.

School impact fees

School districts charge developer fees on new residential space, but under Education Code 17620 and Government Code 66311.5 an ADU under 500 sq ft is treated as construction that does not add 500 sq ft of assessable space, so it owes no school fee. For larger ADUs, the City's current reference sheet (CDD-0226, revised September 2026) lists these residential rates:

District	Per sq ft
Elk Grove Unified	$7.23
Sacramento City Unified	$5.38
San Juan Unified	$5.38
Twin Rivers Unified	$5.38
Natomas Unified	$5.17
Robla Elementary	$2.90 (plus $2.48 for Twin Rivers in the Robla area)

For a 750 sq ft ADU in Sacramento City Unified that is about $4,035. The district sets the final figure when you pay, so treat these as reference rates.

Water, sewer and electrical

• Conversions inside existing space (a garage or part of the house) cannot be required to get a new or separate utility connection, and no connection fee or capacity charge can be charged for one (Gov. Code 66311.5(d)).
• Detached and new-build ADUs can be required to connect separately, but the fee must be proportionate to the unit, based on its square footage or plumbing fixture count, and cannot exceed the reasonable cost of the service.
• Water meter: the City notes that ADUs generally do not need a separate water meter.
• Sewer: sewer impact fees are set by SacSewer, not the City, which is why the City estimate leaves them blank. Ask for the figure for your parcel before you finalize the budget.
• Electrical panel: a detached ADU often means upgrading the main house's panel and service. Whether yours needs it depends on the existing panel, the ADU's loads and solar, so it is worth checking at the first site visit rather than discovering it at plan check.

What drives the construction cost

Fees are a few percent of the project. The build is the rest, and these are the decisions that move it most:

• Type. Converting a garage reuses the slab, walls and roof; a detached ADU needs all of them new. An attached ADU sits in between.
• Size and layout. Kitchens and bathrooms are the most expensive square footage. A studio with one bathroom costs less per unit but often more per square foot than a two-bedroom.
• Utility runs. The distance from the main house to the ADU for sewer, water and electrical trenching adds up quickly on a deep lot.
• Site. Slope, trees, access for equipment and soil all show up in foundation and site-work cost.
• Plans. The City's free Shelf Ready plans remove most design cost, but they cannot be modified, only mirrored.

For a statewide reference point, a UC Berkeley Center for Community Innovation and Terner Center survey of California ADU owners (published 2021) found a median construction cost of $150,000, or about $250 per sq ft. Costs have moved since then and vary widely by type and site, so the only number that matters for your project is a written estimate on your lot. Our current published starting price for a custom ADU is on our ADU construction page.

Property taxes after you build

Building an ADU does not reassess your whole property. Under California Revenue and Taxation Code sections 70 and 71, the assessor sets a new base value only for the newly constructed portion; the base value of the rest of the property does not change.

Sacramento County is different

If your home is in unincorporated Sacramento County rather than the City, the County has its own free Shelf Ready plans (460, 870, 1,000 and 1,184 sq ft) and its own fees. The County notes that ADUs over 750 sq ft are subject to impact fees and that standard building fees apply even with its free plans.

FAQ

Is a 750 sq ft ADU exempt from impact fees in Sacramento?

Under state law since January 1, 2026, yes: the exemption covers ADUs of 750 sq ft of interior livable space or less. The City's 2026 fee estimate still shows impact fees at exactly 750 sq ft, so confirm the treatment at plan review.

Do I pay school fees on a garage conversion?

Not if the ADU is under 500 sq ft of interior livable space: state law treats it as adding no assessable space for school fees. Larger conversions pay the district's residential rate.

How much are permit fees for an ADU in Sacramento?

On the City's 2026 estimate, about $5,300 for a 749 sq ft ADU and about $14,800 for 1,200 sq ft, before school and sewer fees. Building permit fees are based on the City's valuation, so they scale with size.

Can the City make me install a separate water meter?

For an ADU inside existing space, no new or separate connection can be required. For other ADUs, the City states that a separate water meter is generally not required.

Sources: California Government Code 66311.5 (as amended by SB 543, Stats. 2025, ch. 520, effective January 1, 2026); Education Code 17620; Revenue and Taxation Code 70 and 71; City of Sacramento ADU Fee Estimate CDD-0419 (rev. 07-12-2026), ADU Application CDD-0009, School District Impact Fees CDD-0226 (rev. 09-09-2026), ADU Resource Center (costs and Shelf Ready plans); Sacramento County Shelf Ready ADU plans; SacSewer residential rates; UC Berkeley CCI and Terner Center ADU survey (2021). Checked October 2026. Fees change; confirm current figures with the City and your school district before budgeting.