Big Horn County, Montana Building Permit Guide

Big Horn County has no building, planning or zoning department and is not a state-certified building-code jurisdiction. Inside Hardin, the City’s Building and Code Department requires a building permit for homes and other structures; the State certifies it for residential building only, so a commercial building there goes to the Montana Building Codes Program. Outside Hardin and outside the Crow and Northern Cheyenne reservations, the State permits commercial buildings and a house with fewer than 5 units needs no building permit. A new septic system costs $475 to permit when a certified installer does the work.

Which permits apply in Big Horn County?

The answer turns on whether the lot is inside Hardin.

Inside Hardin city limits: the City Code requires a building permit from the City’s building inspector before any building or structure is erected, constructed, moved, expanded or structurally altered. Hardin has written its code to reach buildings the state code leaves out. The code names single-family and multi-family housing, private garages and storage structures, farm or ranch buildings, patios, decks and porches, with only mine buildings, refineries, pulp and paper mills and state-inspected power generation structures exempted.

Within 1 mile of Hardin’s boundary: the Hardin City Code says the County Commissioners let the City control land use for 1 mile beyond the city limits, and it requires a zoning compliance permit from the City before a new land use starts there. New homes, mobile homes, businesses and large animals are the examples the code gives. The permit is free and is not a building permit.

Outside Hardin, the County issues no building permit. On land outside the Crow and Northern Cheyenne reservations, the State requires its own building permit for commercial buildings and for residential buildings of 5 or more units. Houses with fewer than 5 units, farm and ranch buildings and private garages or storage buildings kept for the owner’s use are exempt from it.

Two County requirements stand apart from the building code:

• Septic permit: no work on a septic system may begin until the County Sanitarian has issued a permit to construct.
• Rural address: the Clerk and Recorder’s Office and the County’s Enhanced 911 program assign physical addresses, which utilities ask for before connecting service.

Who issues permits in Big Horn County?

How the 2 incorporated places are covered:

• Hardin (population 3,696): the State’s list certifies the City for building, residential only, within city limits. The City Code also lists commercial and industrial buildings among the structures it governs, and the building application the City posts is the State’s own form, addressed to the Building Codes Bureau in Helena. Because the certification is residential only, a commercial project in Hardin falls to the state office. The City Clerk also takes zoning compliance permit applications for new land uses within 1 mile of the city boundary.
• Lodge Grass (population 422): not on the State’s certified list. The published sources do not say whether the Town requires a permit of its own; the town office is at 212 Hester Avenue (406-639-2362).

The County does have 2 planning boards, a County Planning Board and a City-County Planning Board with Hardin, and Hardin posts the City-County board’s jurisdiction map. The State’s directory of local health agencies also lists a Crow Tribal Health Department at Crow Agency (406-679-6567).

Applications, forms and where they go

• Hardin Citizen Portal: the Building and Code Department takes applications online through its portal, which also lets you search permits. The City accepts cash, checks, cards and money orders, and takes card payments online.
• Hardin Accessory Building Application: for an accessory building at a business. The building may not exceed 200 square feet without a variance request, and the applicant appears before the Common Council when it is considered.
• County Septic Permit Application: sent with the fee to Environmental Health; an Installer Report Form follows the final inspection.
• Request for Rural Address Form: filed with the Clerk and Recorder.
• Subdivision review applications: separate County forms for parcels under and over 20 acres.
• State permits: building, electrical, plumbing and mechanical applications are filed with the Building Codes Program online or on paper.

Fees you can budget for

The County’s published fees are for septic permits and sanitation review. The figures below are from the fee table on the current Septic Permit Application; the left amount applies when a County-certified installer does the work and the right amount when the owner installs.

The County’s older process outline, and the text above the table on its septic page, still quote $150 or $300 for a new system; the application form carries the current table. The permit fee includes the final inspection. Sanitation review of a subdivision costs $200 plus $50 per lot for parcels over 20 acres, and $200 plus the state review fees for parcels under 20 acres.

Under the Hardin City Code, the schedule of construction and inspection fees is kept by the finance officer and city clerk and is available from the building inspector (406-665-9260 ext. 106), who sets the fee on each application. The zoning compliance permit for land within 1 mile of the city has no fee.

Electrical, plumbing and mechanical work

Hardin’s certification stops at residential building, so the City issues no trade permits: electrical, plumbing and mechanical permits for work in Hardin come from the Montana Building Codes Program, and the County has no trade program of its own. A state electrical permit is required for electrical work whether or not the building itself needs a permit.

What each office asks for

Hardin’s building inspector sends copies of the application and plans to other City departments and has 30 days from a complete application to issue or deny the permit, or 40 days when the State or a consultant is asked to help with the review.

Steps for a Big Horn County project

Inspections and final approval

Hardin: the building inspector inspects before and during construction. Work has to stay accessible and exposed until it is approved, and the City is not liable for the cost of removing materials to allow an inspection. When the finished work complies, the inspector issues a Certificate of Occupancy.

Septic systems: a final inspection is required before the system is buried, and the County suggests booking it at least a week ahead; the application also requires 24 hours’ notice before any inspection. The installer’s report form is due within 10 days of the final inspection, after which the Sanitarian issues the final permit and keeps the original on file.

State permits: the permit holder calls the state inspector at least 24 hours before an inspection is wanted.

Local points to plan around

Permit life in Hardin: a City building permit is valid for 180 days from issue unless construction has begun, and expires if work is suspended or abandoned for more than 180 days.

Septic permit life: a County septic permit becomes invalid if the system is not installed within 12 months of the issue date.

Loan letters: a lender’s septic system guarantee letter needs a written request with fees, and the County asks for 2 weeks to schedule it.

Rural addresses: a County rural address describes where the structure is and cannot be used as a mailing address.

Hardin’s 1-mile zoning area: a zoning compliance permit application goes to the City Clerk with a legal description and a site plan showing setbacks, dimensions, the number of dwelling or animal units, water, sewer and drainage, and adjacent land uses; drawings need not be professional. The City has 1 week to approve, conditionally approve or deny a complete application.

Fences in Hardin: a fence or wall more than 30 inches high along a required yard needs a permit from the City building official. The code caps fences at 48 inches in a front yard setback and 6 feet along side and rear yards.

Floodplain and zoning in Hardin: the City Code has its own floodplain regulations (Title 4, Chapter 11) and zoning title (Title 11), and the City posts a zoning map.

Montana building code

Montana adopts one building code, based on the 2024 International Codes from 26 September 2026; a certified local program or the state Building Codes Program enforces it, and the state code does not reach houses of fewer than five units, farm and ranch buildings or private garages unless a local government has made it apply to them. How Montana’s statewide code works

Official permitting resources for Big Horn County

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

• Montana effective construction code editions
• Montana certified local building programs
• Montana DLI state building permit application
• Big Horn County Environmental Health: septic permitting and fee table
• City of Hardin Building and Code Department and Citizen Portal
• City of Hardin permits and forms
• Hardin City Code, Title 4, Chapter 8: building permits, enforcement and fees
• Hardin City-County Planning Board
• Big Horn County Septic Permit Application and fee table
• Big Horn County subdivision sanitation review
• Big Horn County Clerk and Recorder: rural addressing
• Big Horn County Environmental Health: County page with the Sanitarian’s Office phone and address
• Hardin City Code 11-1-11-4: zoning compliance permit within 1 mile of the city

Big Horn County permit FAQs

Does Big Horn County issue building permits?

No. The County has no building department and is not a state-certified building-code jurisdiction. Hardin issues building permits inside its city limits, and the state Building Codes Program permits commercial buildings there and on other land under state jurisdiction.

Do I need a permit to build a house outside Hardin?

Not a building permit, if the building has fewer than 5 dwelling units and the land is under state jurisdiction. Within 1 mile of Hardin a new home needs the City’s free zoning compliance permit. You also need a County septic permit before installing a septic system, and state electrical and plumbing permits where they apply.

Do I need a permit for a deck or garage in Hardin?

Yes. Hardin’s code lists patios, decks, porches and private garages among the structures that need a City building permit, and a fence over 30 inches high along a required yard needs a permit from the building official.

How much is a septic permit in Big Horn County?

$475 for a new system installed by a certified installer and $675 if you install it yourself, site visit included. In an approved subdivision the fees are $150 and $300.

How long does Hardin take to issue a building permit?

The City Code gives the building inspector 30 days from a complete application, or 40 days if outside review is needed.

Who issues electrical permits in Hardin?

The State of Montana. Hardin is certified for residential building only, so electrical and plumbing permits come from the state Building Codes Program.

What is the phone number for septic permits?

Big Horn County Environmental Health is on 406-665-8720, and the Sanitarian’s Office on 406-665-8724. The County’s Environmental Health page and the septic application give 809 N Custer Avenue in Hardin; the Public Health Department’s site gives 200 N Mitchell Avenue.

Simplify Big Horn County permitting with Alliance Permitting

Alliance Permitting is a permit documentation and submission company in Montana. 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 Big Horn County permitting. Requirements, fees, and procedures change; confirm details with the permitting authority before relying on them.