GetYourPermit

ADU permit cost and fee breakdown in San Mateo, California

GetYourPermit’s researched permit-fee range for a detached accessory dwelling unit in San Mateo, with category estimates and direct reference links used in our investigation.

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4 fee lines

ADU size

California prohibits development impact fees for ADUs of 750 sq ft or less, so the 749 / 750 / 751 steps are worth comparing.

400 sq ft500 sq ft749 sq ft750 sq ft751 sq ft1,000 sq ft1,200 sq ft

Estimated total

GetYourPermit researched range at 750 sq ft

$5,732 – $9,332

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

$7,232

Modeled at the 600 sq ft reference.

Where the money goes

These are fee components within the permit process, not separate approvals.

  • Building permit issuance$2,832

    The permit issuance charge; where plan check is bundled, the combined amount is carried here.

  • School district fees$2,400 – $3,300

    Possible school-district developer fees based on current thresholds and scope.

  • Utility fees$300 – $2,100

    Possible water, sewer, electrical, meter, or capacity-related charges.

  • Surcharges, taxes & state fees$200 – $1,100

    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.

FeeAmountBasisSource
New accessory dwelling unit permit fee$2,832Flat fee
Adopted Comprehensive Fee Schedule: 2026-2027Location: 2026-27 Comprehensive Fee Schedule, Building — Accessory Dwelling Units; ADU page, ADU/JADU Permit FeesConfirms: City publishes a $2,831.57 new-ADU flat fee.
Remodel accessory dwelling unit permit fee$2,031Flat fee
Adopted Comprehensive Fee Schedule: 2026-2027Location: 2026-27 Comprehensive Fee Schedule, Building — Accessory Dwelling Units; ADU page, ADU/JADU Permit FeesConfirms: City publishes a $2,031.12 remodel-ADU flat fee.
Pre-approved ADU permit fee$1,455Flat fee
Adopted Comprehensive Fee Schedule: 2026-2027Location: 2026-27 Comprehensive Fee Schedule, Building — Accessory Dwelling UnitsConfirms: City publishes a $1,455.43 pre-approved-ADU fee.
Junior accessory dwelling unit permit fee$1,454Flat fee
Adopted Comprehensive Fee Schedule: 2026-2027Location: 2026-27 Comprehensive Fee Schedule, Building — Junior Accessory Dwelling Units; ADU page, ADU/JADU Permit FeesConfirms: City publishes a $1,454.02 JADU flat fee.

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 San Mateo before you commit money.

City reference pages for verification

Back to San Mateo · Permit process · Build a permit report · How we build these estimates