Macon County, Illinois Building Permit Guide

The Macon County Planning & Zoning Department issues building permits and enforces the International Building Code for new construction and remodels outside the incorporated cities, villages and towns. Of the county’s 99,300 residents (latest Census estimate), 12,386 live in the unincorporated balance and 67,884 in Decatur.

This guide covers the county’s permits for unincorporated land and the City of Decatur, the county seat.

What requires a building permit in Macon County?

A permit must be obtained before work begins; the county’s FAQ says the fee is doubled if you forget to apply. Commercial work needs an engineer-stamped plan set; residential work needs a full set of plans and a copy of the contract.

Illinois leaves building codes to local government, but since 1 January 2025 any local code must regulate structural design at least as strictly as baseline editions of the International Building, Existing Building and Residential Codes, and where no code was adopted the statute sets minimums for commercial buildings and new homes (Public Act 103-0510). Illinois codes and the statewide baseline

Who handles permitting in Macon County?

Planning & Zoning also staffs the Macon County Regional Planning Commission.

Macon County permit costs and fees

• Construction: .3% of project cost for residential and .4% for commercial.
• Accessory structures (garages, post-frame barns, sheds, decks, porches): valued at $25.00 per square foot, so a 500 SF garage works out to $87.50.
• Flat fees: in-ground pool $100.00; demolition $25.00; electrical service or upgrade $75.00.
• On every building permit: a $25.00 administrative fee; the minimum fee is $25.00.
• Penalties: building without a permit or against approved documents costs double the original permit fee, and no certificate of occupancy is issued until it is paid. Demolition without a permit is fined $250 for a first offense, $500 for a second and $1,000.00 after that.
• Zoning petitions: rezoning or special use on 5 acres or less $200.00; a variance or appeal $200.00 regardless of size.

Septic, wells and geothermal loops

The Macon County Health Department reviews plans and issues permits for septic systems and private water wells and inspects their installation. Closed loop (geothermal) well systems must be permitted too, must use food grade propylene glycol as coolant, and are inspected by the Health Department after installation.

How to get a building permit in Macon County

A building permit carries a validity period set by the county or city that issues it; confirm the expiry on phased or delayed work before it passes. Permit validity in Illinois

Building codes in Macon County

The county’s building code FAQ lists the 2015 International Code Council codes and the 2014 National Electrical Code. That is what the FAQ lists; confirm the edition in force with Planning & Zoning. Decatur has enforced the 2021 International Building and Residential Codes, the 2017 National Electric Code and the 2014 Illinois Plumbing Code since January 1, 2024.

Inspections in Macon County and Decatur

County re-inspections cost $150.00, and so do inspections outside normal business hours (8:30 A.M. - 4:30 P.M. Monday-Friday).

In Decatur, permits are requested through the city’s OpenGov platform and inspections are requested online. Requests submitted before 4:00pm the day before are typically scheduled for the next day, routed geographically, and the inspector calls at least 20 minutes before arrival.

Official Macon County permitting resources

These are the primary sources behind this guide. Codes, fee schedules and procedures change — confirm the position for your filing date.

• Macon County Planning & Zoning
• Macon County applicant checklist and fee schedule
• Macon County Health Department environmental health
• Decatur Building Inspections
• Decatur building permits
• Decatur building code information

Frequently asked questions

What does a garage permit cost in unincorporated Macon County?

Accessory structures are valued at $25.00 per square foot; the county’s example is a 500 SF garage at $87.50.

Does a geothermal loop need a permit in Macon County?

Yes. Closed loop well systems must be permitted, use food grade propylene glycol and are inspected by the Health Department.

How fast are Decatur inspections?

Online requests submitted before 4:00pm the day before are typically scheduled for the next day.

Simplify Macon County permitting with Alliance Permitting

• Confirm whether the county or a city or village has the parcel, and which office to file with
• Line up the health, highway and floodplain approvals that come before the building permit
• File with the right office and keep inspections on schedule

Alliance Permitting is a permit documentation and submission company in Illinois. We prepare your paperwork, file it correctly and coordinate with the permitting authority through issuance. We are not a contractor and we do not perform licensed plan review or inspections; that work stays with your licensed team and the jurisdiction.

This guide is provided by Alliance Permitting for general information about Macon County permitting. Requirements, fees, and procedures change; confirm details with the permitting authority before relying on them.