ADU permit cost and fee breakdown in Thousand Oaks, California
GetYourPermit’s researched permit-fee range for a detached accessory dwelling unit in Thousand Oaks, with category estimates and direct reference links used in our investigation.
Prepared by GetYourPermit editorial teamReport an error
ADU size
California prohibits development impact fees for ADUs of 750 sq ft or less, so the 749 / 750 / 751 steps are worth comparing.
Estimated total
GetYourPermit researched range at 750 sq ft
$5,403 – $9,908
This estimate combines our fee-schedule research and project-planning experience. Actual charges vary by parcel, plans, valuation, utilities, and outside agencies.
Typical planning amount
$6,928
Modeled at the 600 sq ft reference.
Where the money goes
These are fee components within the permit process, not separate approvals.
- Separate planning / zoning fee$754
Shown only where the City bills Planning or zoning review as a separate fee.
- Building plan check$1,119 – $1,550
The Building Division’s review of the drawings; part of the Building Permit process.
- Building permit issuance$1,100 – $1,800
The permit issuance charge; where plan check is bundled, the combined amount is carried here.
- Separate trade permits$250 – $650
Shown separately only where electrical, plumbing, or mechanical permits are billed outside a combination permit.
- School district fees$1,700 – $2,800
Possible school-district developer fees based on current thresholds and scope.
- Utility fees$200 – $1,700
Possible water, sewer, electrical, meter, or capacity-related charges.
- Processing, inspection & records$240 – $500
Fixed processing, inspection, records, and administrative charges.
- Surcharges, taxes & state fees$40 – $154
Percentage surcharges, construction taxes, and State-mandated charges.
The darker segment is the low end of the range; the full bar is the high end.
Published fee references
Building permit issuance
The permit issuance charge; where plan check is bundled, the combined amount is carried here.
| Fee | Amount | Basis | Source |
|---|---|---|---|
| Single-family residential / duplex building-permit fee | Verify on the City’s official website | Formula | Adopted Citywide User Fees, Fines, and Penalties — FY 2025-26 and FY 2026-27Location: Page 2, Building Permit Fee — Single-Family Residential / Duplex, all area bandsConfirms: The current two-year schedule publishes graduated building-permit amounts by project square footage for single-family/duplex new work, remodels, and additions. |
| Permit Application Fee | $55 | Flat fee | Adopted Citywide User Fees, Fines, and Penalties — FY 2025-26 and FY 2026-27Location: Page 2, Building Permit Fee — Single-Family Residential / Duplex, Permit Application rowConfirms: The schedule lists a $55 permit-application fee per permit. |
| Permit Issuance Fee | $65 | Flat fee | Adopted Citywide User Fees, Fines, and Penalties — FY 2025-26 and FY 2026-27Location: Pages 2–3, Building, Mechanical, Plumbing, and Electrical Permit Issuance rowsConfirms: The schedule lists a $65 issuance fee for each applicable building or trade permit. |
| Residential mechanical permit fee | Verify on the City’s official website | Per square foot | Adopted Citywide User Fees, Fines, and Penalties — FY 2025-26 and FY 2026-27Location: Page 3, Mechanical Permit Fees, Residential Mechanical Fee (Part of New Construction / Remodel)Confirms: The current two-year schedule lists the residential mechanical permit component at $0.18 per square foot. |
| Residential plumbing permit fee | Verify on the City’s official website | Per square foot | Adopted Citywide User Fees, Fines, and Penalties — FY 2025-26 and FY 2026-27Location: Page 3, Plumbing Permit Fees, Residential Plumbing Fee (Part of New Construction / Remodel)Confirms: The current two-year schedule lists the residential plumbing permit component at $0.18 per square foot. |
| Residential electrical permit fee | Verify on the City’s official website | Per square foot | Adopted Citywide User Fees, Fines, and Penalties — FY 2025-26 and FY 2026-27Location: Page 4, Electrical Permit Fees, Residential Electrical Fee (Part of New Construction / Remodel)Confirms: The current two-year schedule lists the residential electrical permit component at $0.18 per square foot. |
Plan check
Review of your drawings for code compliance.
| Fee | Amount | Basis | Source |
|---|---|---|---|
| Single-family / duplex plan review | 85% formula | Formula | Adopted Citywide User Fees, Fines, and Penalties — FY 2025-26 and FY 2026-27Location: Page 3, Plan Review Fees, Single-Family / Duplex Plan Review rowConfirms: The schedule sets single-family/duplex plan review at 85% of the building-permit fee. |
| Accessory Dwelling Unit Community Development Fee | $754 | Flat fee | Adopted Citywide User Fees, Fines, and Penalties — FY 2025-26 and FY 2026-27Location: Page 8, Community Development, Accessory Dwelling Unit rowConfirms: The adopted schedule lists an ADU-specific Community Development fee of $754 each. |
| Mechanical plan-review fee | 85% formula | Formula | Adopted Citywide User Fees, Fines, and Penalties — FY 2025-26 and FY 2026-27Location: Page 3, Mechanical Permit Fees, Mechanical Plan Review Fee rowConfirms: The current two-year schedule sets mechanical plan review at 85% of the mechanical permit fee. |
| Plumbing plan-review fee | 85% formula | Formula | Adopted Citywide User Fees, Fines, and Penalties — FY 2025-26 and FY 2026-27Location: Page 3, Plumbing Permit Fees, Plumbing Plan Review Fee rowConfirms: The current two-year schedule sets plumbing plan review at 85% of the plumbing permit fee. |
| Electrical plan-review fee | 85% formula | Formula | Adopted Citywide User Fees, Fines, and Penalties — FY 2025-26 and FY 2026-27Location: Page 4, Electrical Permit Fees, Electrical Plan Review Fee rowConfirms: The current two-year schedule sets electrical plan review at 85% of the electrical permit fee. |
Technology & surcharges
Records, technology, and general plan surcharges.
| Fee | Amount | Basis | Source |
|---|---|---|---|
| Technology Fee | Verify on the City’s official website | Percent of valuation | Adopted Citywide User Fees, Fines, and Penalties — FY 2025-26 and FY 2026-27Location: Page 3, Technology Fee rowConfirms: The schedule lists the technology fee as 0.03% of building-permit valuation. |
Surcharges, taxes & state fees
Percentage surcharges, construction taxes, and State-mandated charges.
| Fee | Amount | Basis | Source |
|---|---|---|---|
| Building Standards Administration Special Revolving Fund fee | From $1 | Formula | Adopted Citywide User Fees, Fines, and Penalties — FY 2025-26 and FY 2026-27Location: Page 3, Building Standards Admin. Special Revolving Fund (SB 1473) rowsConfirms: The current two-year schedule publishes the SB 1473 valuation bands and the $1 increment above $100,000. |
| Residential Strong Motion Instrumentation Program fee | Set by City formula | Formula | Adopted Citywide User Fees, Fines, and Penalties — FY 2025-26 and FY 2026-27Location: Page 3, SMIP — For Residential buildings rowConfirms: The current two-year schedule publishes the residential SMIP rate as $0.13 per $1,000 of valuation. |
These are estimates, not official fees
Use these figures for early budgeting only. They are not a quote, not a government fee determination, and not legal advice. Actual fees depend on your parcel, your plans, your construction valuation, your utility provider, and the fee schedule in force on the day your permit is issued. Confirm every number with Thousand Oaks before you commit money.
City reference pages for verification
Back to Thousand Oaks · Permit process · Build a permit report · How we build these estimates