ADU permit cost and fee breakdown in Atherton, California
GetYourPermit’s researched permit-fee range for a detached accessory dwelling unit in Atherton, with category estimates and direct reference links used in our investigation.
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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
$2,800 – $9,600
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
$5,800
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$0 – $1,860
Shown only where the City bills Planning or zoning review as a separate fee.
- Building plan check$650 – $1,800
The Building Division’s review of the drawings; part of the Building Permit process.
- Building permit issuance$900 – $2,100
The permit issuance charge; where plan check is bundled, the combined amount is carried here.
- Separate trade permits$350 – $950
Shown separately only where electrical, plumbing, or mechanical permits are billed outside a combination permit.
- School district fees$500 – $1,400
Possible school-district developer fees based on current thresholds and scope.
- Utility fees$250 – $950
Possible water, sewer, electrical, meter, or capacity-related charges.
- Processing, inspection & records$70 – $210
Fixed processing, inspection, records, and administrative charges.
- Surcharges, taxes & state fees$80 – $330
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 |
|---|---|---|---|
| ADU building valuation basis | Verify on the City’s official website | Formula | Town of Atherton Master Fee Schedule, FY 2026-27Location: Attachment 5, Building Fees, rows 1–6; Master Fee Schedule page, Building Permit Fee Calculation ExampleConfirms: The current schedule separately gives zero valuation base for an ADU complying with Town setback standards and 50% for other ADUs; the Town page explains the service-requirement valuation methodology. |
| Building Permit and Plan Review by valuation | Set by City formula | Formula | Town of Atherton Master Fee Schedule, FY 2026-27Location: Attachment 5, Effective July 6, 2026, Total Valuation / Building Permit Fee / Plan Review Fee tableConfirms: The current schedule sets a complete valuation-based permit formula and distinguishes 65% versus 45% plan-review percentage at the $500,000 threshold. |
Technology & surcharges
Records, technology, and general plan surcharges.
| Fee | Amount | Basis | Source |
|---|---|---|---|
| Building technology surcharge | 3.5% formula | Formula | Town of Atherton Master Fee Schedule, FY 2026-27Location: Attachment 5, Building Fees, Technology surchargeConfirms: The FY 2026-27 schedule lists a 3.5% Building technology surcharge to fund permit systems and digital plan storage. |
Surcharges, taxes & state fees
Percentage surcharges, construction taxes, and State-mandated charges.
| Fee | Amount | Basis | Source |
|---|---|---|---|
| ADU Planning fee | Verify on the City’s official website | Estimated range | Town of Atherton Master Fee Schedule, FY 2026-27Location: Planning Fees, rows 93–95, Junior accessory dwelling unit / Accessory Dwelling UnitConfirms: The FY 2026-27 Planning fee table gives $0 for a JADU and an ADU complying with Town setback standards, and $1,860 for the other ADU row. |
| General Plan Maintenance and Update surcharge | 2.65% formula | Formula | Town of Atherton Master Fee Schedule, FY 2026-27Location: Attachment 5, Building Fees, Surcharge for General Plan Maintenance and UpdateConfirms: The FY 2026-27 Building fee table lists a 2.65% General Plan Maintenance and Update surcharge. |
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 Atherton before you commit money.
City reference pages for verification
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