If you bought a South Bay home with a converted garage, an extra room, or a back unit that never got a permit, the first question is usually what the city will charge to make it legal. The answer depends on which city the house is in. Every city here makes you pull the permit and pass inspection. What differs is the penalty on top. We collected each city's own published rule into one table so you can see it before you call anyone.
- Most South Bay cities charge a penalty for work done without a permit, and the most common rule is double the normal permit fees.
- The penalty is on top of the work itself. Fixing what the inspector finds is usually the bigger cost.
- An ADU or junior ADU built before January 1, 2020 has a separate path under state law, and several cities run penalty-free programs for it.
- Fee schedules change every year, so confirm the current number with the city before you budget.
Penalty rules by city
| Jurisdiction | Work done without a permit | ADU built before 2020 | Source |
|---|---|---|---|
| San Jose | About 2x city fees A "fee for work without a permit" equal to the permit issuance, plan review and permit fees, so the city's fees roughly double. Owed whether or not a permit is issued. A survey fee of $315 per hour can apply to inspections before a permit. | City AB 2533 program, described by the city as a "penalty-free path". | fee schedule, ADU program |
| Unincorporated Santa Clara County | $842 minimum investigation fee An investigation fee for construction done without a permit, $842.00 minimum. With an open code case, a violation fee adds 100% of the plan check and permit fee. | County AB 2533 legalization program. | building fees, code enforcement fees, ADU program, our County guide |
| Campbell | 2x the permit fee Building without a permit: 2x the permit fee. The Building Official may reduce it if the application comes in by a deadline. | State law applies. | fee schedule |
| Cupertino | Double fees Work without a permit: double fees, based on current permit and plan check fees. | State law applies; the city's ADU code also bars denial for units built before 2020. | fee schedule |
| Los Gatos | Double the application fee Applications for work unlawfully completed: double the current application fee. | State law applies. The Town's own ADU code still uses an older January 1, 2018 cutoff, but state law sets January 1, 2020. | fee schedule, our Los Gatos guide |
| Milpitas | Investigation fee An inspection investigation fee for construction without permits. | Safe ADU Legalization Program for units built before 2020. | fee schedule, ADU program |
| Monte Sereno | Double fees Work started without a permit: an added fee equal to the base fees, which the schedule calls double fees. | State law applies. | fee schedule |
| Mountain View | No multiplier in the fee schedule No penalty multiplier appears in the adopted fee schedule. Code compliance inspections are billed as their own line item. | Legalize Existing ADU program; the city says no code enforcement action or penalties for qualifying units. | building fees, ADU program |
| Santa Clara (city) | 2x the permit fee A fee for work started before a permit is issued, equal to the permit fee, so the permit fee doubles. | State law applies. | fee schedule |
| Saratoga | 2x the permit fee Building without a permit: penalty of 2x the permit fee. | State law applies. | fee schedule, our Saratoga guide |
| Sunnyvale | Penalty added, multiplier not published The building code adds penalty fees on top of the permit fee for work done without one. The city does not publish whether that works out to 2x or 3x in practice. | State law applies. | municipal code |
Not covered yet: Palo Alto, Los Altos, Los Altos Hills, Gilroy and Morgan Hill. If your home is in one of those, call us at (408) 667-4946 and we will check that city's rule for you.
What the table does not tell you
The penalty is usually the smallest part of the bill. The city inspects what was built, and the inspector may need walls, ceilings or floors opened to see framing, wiring and plumbing. Anything that does not meet current code gets corrected. None of these cities publishes a fixed rule for how much has to be opened, so we agree the scope with the inspector before the work starts.
Some cities also add charges for investigation time, re-inspections, or an open code enforcement case. A case that sits open usually costs more than one that is resolved early, because fines and staff time keep adding up. If you already have a notice, read our guide to resolving a code violation.
ADUs built before 2020
If the unpermitted space is a living unit, an ADU or junior ADU, built before January 1, 2020, state law (Government Code 66311.7) limits how a city can deny the permit. San Jose, the County, Milpitas and Mountain View run their own programs for it. In the other cities the state law still applies even where the city's own code has not caught up. Our guide to California's ADU amnesty covers who qualifies.
How we handle it
We start by pulling the permit history for the address and looking at the work in person, so you know which path you are on and roughly what it costs before you commit. Then we coordinate the as-built drawings, walk the project through plan check and inspections, and do the corrective work. For San Jose specifics, see our guide to legalizing an unpermitted addition.
Sources
- City of San Jose: Building and Structure Permits Fee Schedule (effective August 10, 2026)
- City of San Jose: AB 2533 ADU and JADU Legalization Program
- County of Santa Clara: Building Fee Schedule
- County of Santa Clara: Code Enforcement Fee Schedule
- County of Santa Clara: AB 2533 Legalization of Accessory Dwelling Units Program
- City of Campbell: FY 2027 Master Fee Schedule (effective July 1, 2026)
- City of Cupertino: Building Fee Schedule
- City of Santa Clara: Municipal Fee Schedule
- Sunnyvale Municipal Code Chapter 16.16 (building code amendments)
- City of Saratoga: Adopted Fee Schedule (effective July 1, 2026)
- Town of Los Gatos: FY 2026-27 fee schedule (Town Council packet)
- City of Milpitas: Building Fee Schedule (effective August 3, 2026)
- City of Milpitas: Safe ADU Legalization Program
- City of Monte Sereno: Master Fee Schedule (effective August 5, 2024)
- City of Mountain View: Building Permit Fees
- City of Mountain View: Legalize Existing ADU
- California Government Code Section 66311.7 (unpermitted ADUs built before 2020)