Mountain View, CA Accessory Structures: ADU Impact Fees (2026)
Key Facts
- Fee basis
- Per new dwelling unit, Sec. 43.5.b.1
- ADU exemption
- Full exemption, Sec. 43.8.a.3
- Also exempt
- Affordable housing, temporary uses
- Fee timing
- Paid before building permit issued
- Appeals
- Zoning administrator, then council hearing
Summary
Mountain View exempts accessory dwelling units from its citywide transportation impact fee under City Code Sec. 43.8.a.3. The fee otherwise applies per new dwelling unit for residential development citywide, but ADUs defined in Chapter 36 are carved out entirely, alongside affordable housing units and temporary uses.
a.The following are exempt from the fee:1.Government and nonprofit facilities. Public park facilities and buildings which are owned and at least seventy-five (75) percent occupied by governmental or nonprofit agencies and organizations.2.Affordable housing. Because affordable housing is an important community need, the affordable housing units included in new development projects shall not be included in the total number of dwelling units used to calculate the transportation impact fee.3.Accessory dwelling units, as defined in Chapter 36.4.Temporary uses, as defined in Chapter 36.
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: Code of Ordinances: Supplement 34 Update 4).
Full Breakdown
Chapter 43 imposes a citywide transportation impact fee on traffic-generating development, set by council resolution and adjustable annually by the San Francisco Engineering News-Record Construction Cost Index (Sec. a). Residential projects are charged the fee per new dwelling unit (Sec. 1), and the fee must be paid in full before a building permit is issued or a subdivision map is recorded (Sec. c). 8 lists exemptions from that fee: government and nonprofit facilities occupied at least 75 percent by such agencies, affordable housing units in qualifying developments, and, at item 3, accessory dwelling units as defined in Chapter 36.
Temporary uses, parking structures, residential additions creating no new units, interior remodels with no new floor area, and repair/replacement work are also exempt under the same section. 1 for qualifying housing developments that meet trip-reduction criteria, decided by the zoning administrator based on a transportation impact analysis. Because the ADU exemption in item 3 is unconditional, unlike the housing-development reduction in subsection b, an ADU builder does not need to submit a trip study or meet density-bonus criteria to avoid the fee; the exemption applies simply because the unit is an ADU under Chapter 36.
Violations & Fines
There is no separate ADU-specific penalty; the general fee-payment rule controls. If a project is later found not to qualify as an ADU, or misrepresents its status, the transportation impact fee must be paid in full before a building permit is issued or a subdivision map recorded (Sec. 43.5.c). Classification disputes go to the zoning administrator, and appeals of a zoning administrator's impact-fee determination are filed under Sec. 43.9 for a public hearing before the city council per Section 36.56.
Frequently Asked Questions
Does Mountain View charge a transportation impact fee for an ADU?
Does the ADU still need any impact fee analysis?
What other projects share the ADU exemption?
Sources & Official References
Other rules in Mountain View
California rules heatmap·Compare Mountain View to another location·View the California accessory structures overview
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