Folsom, CA Accessory Structures: ADU Impact Fees (2026)
Key Facts
- Full exemption, ADU
- 750 sq ft or less
- Full exemption, JADU
- 500 sq ft or less
- Larger ADU fee method
- Prorated by floor-area ratio
- Water/sewer connection fee
- Not a new use unless new primary home
- Fee-setting body
- City Council by resolution
Summary
Folsom cannot charge city impact fees on an ADU of 750 square feet or less, or a JADU of 500 square feet or less. Larger ADUs pay impact fees prorated by square footage compared to the primary home, not the full new-home rate.
C. Impact Fees. 1. For the purposes of this subsection, impact fees do not include any connection fee or capacity charge for water or sewer service. 2. No city-imposed impact fees shall be charged to an accessory dwelling unit that is seven hundred fifty square feet or less in floor area, or a junior accessory dwelling unit that has five hundred square feet or less in floor area. 3. For accessory dwelling units more than seven hundred fifty square feet, city-imposed impact fees shall be charged proportionately in relation to the square footage of the primary dwelling unit (e.g., the floor area of the accessory dwelling unit, divided by the floor area of the primary dwelling unit, times the typical fee amount charged for a new dwelling).
Official source re-checked September 8, 2026: no newer edition of the code had been published (publisher’s edition: current through Ordinance 1369, passed April 28, 2026).
Full Breakdown
060(C) of the Folsom Municipal Code sets the city's ADU impact fee structure. Impact fees, defined to exclude water and sewer connection fees or capacity charges, cannot be charged at all on an ADU of 750 square feet or less in floor area or a JADU of 500 square feet or less. For an ADU larger than 750 square feet, the city must prorate its impact fees using a ratio of the ADU's floor area divided by the primary dwelling's floor area, multiplied by the typical fee charged for a new dwelling, rather than billing the full new-construction rate.
If another agency or special district, not the city, imposes impact fees that the city collects on its behalf, the city passes those through according to that agency's own fee schedule rather than Folsom's proration formula. 040(C) applies the same non-new-use treatment to general utility connection fees and capacity charges. 060(A), and any unit routed through planning review pays a separate application fee set by city council resolution. 105's purpose clause, Government Code Title 7, Division 1, Chapter 13, which the chapter states controls wherever it conflicts with the local code.
Violations & Fines
The fee exemption is self-executing under the ordinance text: a qualifying small ADU or JADU is not billed impact fees in the first place, so there is no separate penalty provision to enforce. A permit applicant who believes the city miscalculated a prorated fee on a larger ADU can raise that dispute through the standard application review and appeal path in Section 17.105.050(D), which routes appeals of community development director decisions to the planning commission within 60 business days.
Frequently Asked Questions
Does Folsom charge impact fees on a small ADU?
How are impact fees calculated on a larger Folsom ADU?
Will adding an ADU raise my water and sewer connection fees?
Sources & Official References
Other rules in Folsom
California rules heatmap·Compare Folsom to another location·View the California accessory structures overview
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ADU Impact Fees in Nearby Cities
How other cities in Sacramento County handle adu impact fees.