ADU Pass
Nassau County
ADU Pass helps homeowners in Nassau County, Florida navigate the permit paperwork for building an accessory dwelling unit. We cover 5 cities and 6 ZIP codes in this county.
Map
County ADU details
County ADU ordinance
Nassau County (county seat Fernandina Beach on Amelia Island; northernmost Atlantic-facing Florida county, immediately north of Jacksonville) regulates accessory dwelling units on unincorporated parcels through the Nassau County Land Development Code. Nassau includes Amelia Island (Fernandina Beach and unincorporated Amelia Island South), the rapidly growing Yulee / Wildlight / Nassau Crossing suburban corridor along Interstate 95, and rural western county. Population approximately 95,000 and growing. Florida has no statewide ADU preemption; § 163.31771 FS is permissive only. Pending SB 48 / HB 313 (2026 session) would establish a statewide ADU floor with a December 1, 2026 conformance deadline if enacted. This is Nassau County Florida, NOT Nassau County New York — data consumers should confirm stateSlug === 'florida'.
Code citations:
State-floor overlay: Florida has no statewide ADU preemption as of April 2026. § 163.31771 FS is permissive only. Pending 2026 bills (SB 48 / HB 313) would impose a statewide floor; Nassau's ordinance would need audit against the final statutory text if enacted (December 1, 2026 deadline in current drafts).
Adopting body: Nassau County Board of County Commissioners
County permitting (unincorporated parcels)
Permits for ADUs on parcels in unincorporated Nassau County are issued by the Nassau County Planning & Economic Opportunity Department and the Building Department. Nassau has two incorporated municipalities: Fernandina Beach (on the north end of Amelia Island) and Callahan (a small inland town). Most of Amelia Island south of Fernandina Beach, plus the entire Yulee / Wildlight / Nassau Crossing suburban growth corridor and rural western county, is unincorporated.
Process overview: An ADU on an unincorporated Nassau parcel is permitted as a combined planning/building permit. Typical workflow: zoning-compliance review, construction-drawing submission under Florida Building Code 2023, wind-load review (Nassau Atlantic coast sits in approximately the 140 mph ASCE 7-22 ultimate design wind-speed zone, inland parcels 130 mph), plan review, issuance, inspections, and certificate of occupancy. Amelia Island coastal parcels add FDEP CCCL review. St. Marys River and tidal-creek floodplain parcels require elevation-certificate review. Septic-system parcels (common in rural western Nassau) add FDOH review.
Impact fees: Nassau County levies transportation, schools, fire-rescue, and parks impact fees on new residential units. The Wildlight master-planned community and surrounding I-95 corridor has been one of the fastest-growing markets in northeast Florida; impact-fee rates there reflect infrastructure-demand pressure. ADU additions in unity-of-title configurations receive reduced rates. (schedule)
County assessor
The Nassau County Property Appraiser maintains parcel-level assessment records for all real property in Nassau County, including parcels within Fernandina Beach and Callahan. ADU additions are assessed at just value on completion; Florida's Save Our Homes 3% cap applies to homesteaded primary residences. Amelia Island has a substantial non-homestead second-home inventory that is reassessed annually at just value.
Assessment policy: ADU additions assessed at just value on completion; homesteaded host portion continues under Save Our Homes cap. No county-level ADU abatement or incentive.
County overlays (6)
Nassau County administers coastal, floodplain, wetland, and master-planned community overlays. Amelia Island's Atlantic-facing coast exposes barrier-island parcels to high-risk FEMA flood zones and the CCCL program. Tidal-creek and salt-marsh wetlands along the Intracoastal Waterway, Nassau Sound, and St. Marys River face St. Johns River Water Management District jurisdiction. Several large master-planned communities (Wildlight, Amelia Concourse, Amelia National) impose private architectural review atop the county code.
- FEMA Special Flood Hazard Areas (SFHA) — Coastal A, VE, AE zones — Nassau participates in NFIP. Amelia Island ocean-facing parcels face Zone VE or Coastal A designations; Intracoastal and tidal-creek parcels face Zone AE. ADU construction in Zone VE requires pile/column foundations, breakaway walls, and flow-through venting.
- Coastal Construction Control Line (CCCL) — Parcels seaward of the CCCL on Amelia Island require FDEP CCCL permits in addition to county permits. Amelia Island's Atlantic coast has mixed erosion and accretion patterns; CCCL-imposed foundation setbacks vary by segment.
- St. Johns River Water Management District Environmental Resource Permits — Nassau sits within SJRWMD jurisdiction. ADU site work affecting tidal wetlands, salt marsh, or altering stormwater requires an ERP. Coastal and marsh-adjacent parcels commonly require wetland delineation.
- Hurricane Wind Zone — approximately 130-140 mph ultimate design wind speed — Nassau's Atlantic coast sits in approximately the 140 mph ASCE 7-22 ultimate design wind-speed zone; inland closer to 130 mph. Hurricane Matthew (2016), Irma (2017), Dorian (2019), and Ian (2022) have all produced impact in Nassau.
- Amelia Island Historic District (Fernandina Beach) — The Fernandina Beach Historic District — a National Register district covering downtown Fernandina — imposes architectural and materials-compatibility review on new construction and accessory structures. This is a city-level overlay within Fernandina Beach; unincorporated Amelia Island South does not have a county-level historic overlay.
- Master-planned community private architectural review (Wildlight, Amelia Concourse, Amelia National) — Major master-planned communities in unincorporated Nassau (Wildlight in Yulee, Amelia Concourse, Amelia National) impose private architectural-review-committee approvals atop the county code. An ADU in these communities requires both county permit and ARC approval, and ARC rules may be more restrictive than the county ordinance.
Known county issues (3)
- policy-review — Both bills would impose a statewide ADU floor. Nassau's ordinance would need audit against the final statutory text if enacted (December 1, 2026 conformance deadline in current drafts).
- other — This record is the Florida Atlantic-coast Nassau County (county seat Fernandina Beach), NOT the Long Island New York Nassau County. Data consumers should confirm stateSlug === 'florida' before relying on this record; the two counties have entirely different state law, insurance landscape, and regulatory regime.
- other — Amelia Island's Atlantic exposure has driven private wind insurers out of much of the barrier-island market. Many coastal parcels are insured through Citizens Property Insurance Corp. Florida's 10% hurricane deductible cap means an ADU addition on a coastal Nassau parcel can increase deductible exposure materially.
Florida state — ADU law and programs
State ADU law
Florida does NOT currently have a statewide ADU preemption law in effect. Florida Statutes § 163.31771 (enacted 2004, last amended 2020) is permissive — it authorizes local governments to adopt ADU ordinances but does not require them to. ADU rules are therefore set municipality-by-municipality: Miami-Dade, Orlando, St. Petersburg, Tampa, and a growing set of Florida cities have their own ordinances; many smaller counties and cities still prohibit or restrict ADUs by default. A preemption bill (SB 48 / HB 313) is pending in the 2026 legislative session and is likely to pass given that its 2025 predecessor cleared the Senate 37-0 and House 97-10 before dying on a procedural amendment dispute.
- Florida Statutes § 163.31771 — Accessory dwelling units — Permissive (not mandatory) statute. Defines an ADU as 'an ancillary or secondary living unit, that has a separate kitchen, bathroom, and sleeping area, existing either within the same structure, or on the same lot, as the primary dwelling unit.' Authorizes — but does not require — local governments to adopt ordinances allowing ADUs in single-family residential zones. Contains no size caps, no owner-occupancy rules, no HOA preemption. All substantive rulemaking is local.
State financing programs
Florida Housing Finance Corporation (FHFC) does not operate an ADU-specific state loan or grant program. FHFC's primary affordable-housing lever at the ADU tier is the State Housing Initiatives Partnership (SHIP), which distributes state documentary-stamp-tax revenue to all 67 counties and 52 entitlement cities for locally-administered housing programs — some of which may fund ADU construction at the local level (notably Orange County's Affordable ADU Loan Program, run through the Orange County Housing Finance Trust). FHFC's FL Assist down-payment programs and HFA Preferred / HFA Advantage conventional loans apply to ADU-eligible primary residences but do not single out ADUs. Proposed CS/SB 1440 would create a state property-tax exemption of up to 100% of assessed value for an ADU rented at affordable rates.
State housing programs
Florida does not currently operate a statewide pre-approved ADU plan catalog (unlike California or Washington). State-level ADU implementation is driven by (a) the permissive § 163.31771 which lets willing jurisdictions adopt ordinances, (b) SHIP pass-through funding to local ADU programs (Orange County's Affordable ADU Loan Program is the model), and (c) the affordable-housing property-tax exemption under the Live Local Act (SB 102 / SB 328). The Department of Economic Opportunity (DEO) — now reorganized as the Department of Commerce — provides technical assistance to local governments but no statewide ADU-specific mandate or program. Major counties (Miami-Dade, Orange, Pasco, Hillsborough, Pinellas, Broward) have published their own ADU ordinances and guidance documents.
Federal (United States) — ADU-relevant rules and programs
Federal ADU law
The United States has no federal statute that directly regulates accessory dwelling unit entitlement or design. Land-use authority over ADUs resides with states and local governments under the traditional police power. Federal engagement is limited to financing (Fannie/Freddie/FHA/VA/USDA), flood insurance (FEMA/NFIP), and discretionary housing programs (HUD), which are recorded in sibling sections of this file.
Federal financing programs
Federal housing-finance agencies and GSEs set nationwide underwriting rules that govern whether an ADU can be financed, appraised, and counted toward mortgage qualifying income. The relevant actors are Fannie Mae, Freddie Mac, FHA (HUD), VA, and USDA Rural Development.
Federal tax credits
There is no ADU-specific federal tax credit. ADUs may incidentally qualify for existing federal energy-efficiency and clean-energy tax credits when the ADU construction includes qualifying measures.
Federal housing programs
HUD administers several discretionary programs that can fund ADU-related activity at the grantee's election, but none is an ADU-specific program.