ADU Pass
Madison County
ADU Pass helps homeowners in Madison County, Ohio navigate the permit paperwork for building an accessory dwelling unit. We cover 9 cities and 9 ZIP codes in this county.
Map
County ADU details
County ADU ordinance
Madison County, Ohio (west-central Ohio between Columbus and Springfield along I-70 and US-40; ~44,700 residents; county seat London; 14 townships - Canaan, Darby, Deer Creek, Fairfield, Jefferson, Monroe, Oak Run, Paint, Pike, Pleasant, Range, Somerford, Stokes, Union; one city (London), six villages (Mount Sterling, Plain City - partial, South Solon, West Jefferson, Midway, the south fringe of Plain City), and numerous unincorporated communities (Irwin, Jeffersonville - actually in Fayette County but mirrored, Lafayette, Lilly Chapel, Resaca, Sedalia, Summerford)) is one of the small minority of Ohio counties that HAS adopted a countywide rural zoning resolution under O.R.C. Chapter 303. The Madison County Zoning Resolution (originally adopted 12/1/2006, periodically amended) is administered by the Madison County Planning and Zoning Department (1 N. Main Street, London) and covers 13 of the 14 unincorporated townships countywide; one township (Pleasant) has retained township-level zoning under O.R.C. 519 instead of joining the county resolution. This is a structurally different setup from neighboring Champaign County (Ohio's typical rural pattern of township-tier zoning under O.R.C. 519 for every township with no county resolution). Inside the city of London, the villages, and the Plain City portion within Madison County, municipal zoning controls. The countywide resolution establishes A-1 (Agricultural) and R-1 (Single-Family Residential) as the predominant unincorporated districts; A-1 lots are large (typically 2+ acres) and R-1 lots are platted subdivision parcels. The 2006 resolution does NOT use the term 'accessory dwelling unit' as a defined permitted use; a second dwelling on an A-1 or R-1 parcel is typically pursued either as (a) an accessory structure containing dwelling space (permitted only with explicit BZA approval), (b) a Conditional Use, or (c) a Variance from the single-family-dwelling-per-lot limit. Section 21.12 of the resolution is the Big Darby Scenic Rivers overlay, which imposes additional riparian-setback and impervious-surface limits along the Big Darby Creek federally designated National Scenic River corridor in eastern Madison County (Canaan, Darby, Monroe, Pleasant townships).
County assessor
Assessment policy: The Madison County Auditor (Jennifer Hunter, first elected November 2010, reelected to a fourth term effective 2023-03-13) is the elected property-assessment authority under O.R.C. § 5713.01. Ohio assesses real property at 35% of true value (O.R.C. § 5713.03). New ADU construction is added to the parcel record on the next regular cycle (Ohio counties operate a six-year reappraisal cycle with a triennial update; Madison County's next triennial update is for tax year 2026 / pay year 2027, per the Auditor's published schedule) and reassessed at true value as of January 1 following completion. The Ohio Owner Occupancy Credit (O.R.C. § 323.151 et seq.) provides a 2.5% reduction in tax on owner-occupied homestead; the Homestead Exemption (O.R.C. § 323.152) reduces taxable value by $25,000 for owners 65+ or totally and permanently disabled, subject to income tests. Madison County also administers Current Agricultural Use Valuation (CAUV) under O.R.C. § 5713.30 - § 5713.38; CAUV enrollment in Madison County is high given that row-crop agriculture (corn, soybeans, wheat) dominates the county economy in the central Ohio agricultural plain. An ADU on a CAUV parcel may trigger recoupment (a three-year rollback of the tax differential) if the dwelling reduces qualifying agricultural acreage below program thresholds; CAUV reviewers in Madison County examine ADU additions case-by-case. Under O.R.C. § 5713.17, the owner must notify the Auditor of any construction or improvement valued over $2,000. Board of Revision complaints (property-tax assessment appeals) for Madison County parcels are filed with the County Auditor between January 1 and March 31 each year.
County overlays (5)
Known county issues (5)
- other — ADU applicants in unincorporated Madison County deal with ONE zoning authority (Madison County Planning & Zoning at 1 N. Main, London - 740-852-2833) rather than the township-by-township pattern common in rural Ohio - the exception being Pleasant Township (Mount Sterling) which has its own zoning inspector. BZA calendar time for a Conditional Use or Variance is commonly 45-90 days plus a $200-$600 BZA filing fee.
- other — ADU applicants in unincorporated Madison County submit residential plans through the West Jefferson OpenGov permit portal rather than to a county counter. This is operationally unusual but not procedurally onerous; plan review and inspection follow the Ohio Residential Code under OAC 4101:8 exactly as they would under any certified Ohio building department. State-owned parcels (the London-area prison complex) are excluded and go to Ohio Commerce DIC instead.
- other — ADU projects in Canaan, Darby, Monroe, or Pleasant townships within the Section 21.12 overlay should expect (a) stricter riparian setbacks and impervious-surface limits than elsewhere in the county, (b) potential Section 401 / Section 404 nexus if any wetland or stream crossing is implicated, and (c) coordination with the Ohio DNR Scenic Rivers Program. Add 30-90 days of calendar time and $1,000-$10,000 of consultant cost relative to a comparable unincorporated Madison County parcel outside the overlay.
- other — Enumeration of Madison County cities here includes these cross-county and split entries for fidelity to the city-highlights tree, but consumers should not attribute their full populations to Madison County. The county's wholly-resident incorporated population is dominated by London (~10,060), West Jefferson (~4,279), Mount Sterling (~1,745), and South Solon (~361).
- policy-review — Researchers should monitor the Ohio General Assembly for any future ADU preemption proposal. Until one passes, Madison County ADU permissibility is a parcel-by-parcel question driven by the Madison County Zoning Resolution (or Pleasant Township resolution), the Section 21.12 Darby overlay if applicable, the FEMA SFHA mapping, and CAUV-recoupment exposure on agricultural parcels.
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.