This is PermitBase’s published record for Unincorporated Yellowstone County as of 2026-07-02. It has since been superseded — see the current record. A historical record reflects what PermitBase had verified at that time; it may not capture a real-world change the jurisdiction had made but PermitBase had not yet verified, and it includes any errors we later corrected. Snapshots are never edited retroactively.
Unincorporated Yellowstone County building permits
VerifiedUnincorporated Yellowstone County, Montana — as published 2026-07-02.
Verified 2026-07-02 · Source
Codes adopted
Permit types & fees
Residential Building Permit
VerifiedIn unincorporated Yellowstone County, Yellowstone County itself issues NO building permits or Certificates of Occupancy — confirmed directly by the county: 'Yellowstone County does not issue Building Permits or Certificates of Occupancy for structures outside the city limits of Billings.' Building permit authority instead sits with the Montana Building Codes Bureau (state DLI), EXCEPT that Montana state law exempts private homes and apartment buildings of four or fewer dwelling units (that do not serve transient guests) from the state building permit requirement entirely. Practical effect: most single-family homes, duplexes, triplexes, and fourplexes built in unincorporated Yellowstone County require NO building permit from any government body — county or state — for the structure itself. A state building permit IS required for 5+ unit residential buildings and any non-exempt structure.
Verified 2026-07-02 · Source
Requirements
- New single-family, duplex, triplex, or fourplex dwelling construction is EXEMPT from the state building permit requirement per the Montana Building Codes Bureau FAQ: 'A building permit is not required for a single family residence, unless you live inside a local government's jurisdiction, which requires the permit by ordinance or resolution' — unincorporated Yellowstone County has no such ordinance
- Residential buildings of 5 or more dwelling units (multi-family) DO require a state building permit
- Private garages and private storage buildings for the owner's own personal use are exempt regardless of unit count
- Farm and ranch buildings are exempt
- Confirm applicability directly with the Building Codes Bureau at (406) 841-2056 or buildingcodes@mt.gov before assuming exemption — 'additional work may also be exempt from a building permit and an inquiry to the bureau may be required to determine whether a building permit is required'
- Even when the building itself is exempt, separate state electrical, plumbing, and mechanical permits are still required for that work
Required documents
- OptionalApplication for Building Permit (BCP-1)Required only for non-exempt residential construction (5+ units) or if the Bureau determines a permit is needed. Filed with the Montana Building Codes Bureau, PO Box 200517, Helena, MT 59620-0517, or online at aca-prod.accela.com/bcb. Governed by Title 50, Chapter 60, Section 104, MCA and ARM 24.301-131.
- OptionalConstruction Plans and SpecificationsFor non-exempt projects: site plan, dimensioned floor plan, room-use identification, structural section details, truss/foundation engineering seals where non-standard, materials specifications, and IECC energy-compliance documentation (ComCheck accepted)
Fee schedule
| Fee type | Amount | Notes |
|---|---|---|
| State Building Permit Fee | Calculated based on project valuation (fee schedule not published inline on the application; contact Building Codes Bureau at (406) 841-2056 for the current valuation-based fee table) | Montana Application for Building Permit (BCP-1, Rev. 11/25) — states 'Do not send fees with the submittal, unless you have been assigned a project number'; only applicable to non-exempt (5+ unit) residential or other non-exempt buildings |
Electrical Permit
VerifiedAll electrical work in unincorporated Yellowstone County requires a State Electrical Permit from the Montana Building Codes Bureau, since Yellowstone County is not a certified local government for electrical code enforcement. Homeowners may wire their own home under a Homeowner Electrical Permit; all other work requires a Montana-licensed electrical contractor. Governed by Title 50, Chapter 60, Section 604, MCA and ARM 24.301.431.
Verified 2026-07-02 · Source
Requirements
- Required for any new electrical installation, remodel, or repair statewide except in certified local jurisdictions (per Section 50-60-602, MCA exemptions and certified-government list — Yellowstone County is not certified)
- Homeowners may self-perform wiring on their own home, garage, and premises via a Homeowner Electrical Permit — 'Is this permit for work to be done to property you own and maintain for your own personal use?' and 'Will you personally be performing the electrical work?' must both be answered yes
- All other electrical work must be performed by a Montana-licensed electrical contractor (UCO or LCO license) pulling a Residential or Commercial Electrical Permit
- Alternative energy (solar/wind/hydro) connections that are grid-tied require a licensed electrical contractor for the final connection even if a homeowner self-installs the rest
Required documents
- RequiredApplication for Residential Electrical PermitFiled by a licensed electrical contractor (UCO/LCO license required) with the Building Codes Bureau, PO Box 200517, Helena, MT 59620-0517, or online at aca-prod.accela.com/bcb
- OptionalApplication for Homeowner Electrical PermitUsed instead of the residential contractor application when the property owner personally performs the wiring on their own primary residence
Fee schedule
| Fee type | Amount | Notes |
|---|---|---|
| Single Family Dwelling — Up to 200-amp service | $200 | Montana Building Codes Bureau, Application for Residential/Homeowner Electrical Permit (ARM 24.301.431, Rev. 11/25), option A |
| Single Family Dwelling — 201 to 400-amp service | $380 | Same source, option B |
| Single Family Dwelling — 401 to 600-amp service | $600 | Same source, option C |
| Single Family Dwelling — 601-amp service and up | $800 | Same source, option D |
| Interior/Exterior Wire or Rewire — 4+ circuits & change of service/interior panel | $120 | Same source, option E |
| Interior/Exterior Wire or Rewire — 4+ circuits (no panel/service change) | $100 | Same source, option F |
| 2-3 additional circuits or pieces of equipment | $70 | Same source, option G |
| 1 additional circuit or piece of equipment | $45 | Same source, option H |
| Residential Change of Service — exterior meter base/main disconnect only | $45 | Same source, option I |
| Residential Change of Service — disconnect w/ feeder & distribution panelboard replacement | $75 | Same source, option J |
| Alternative Energy connection (residential change of service) | $45 | Same source, option K |
| Private Property Accessory Building (garage, etc.) — up to 200-amp panel | $80 | Same source, option L |
| Private Property Accessory Building — 201 to 300-amp panel | $150 | Same source, option M |
| Private Property Accessory Building — 301-amp panel | $250 | Same source, option N |
| Construction Service (Provisional Power) | $60 | Same source, option AA |
| Livestock wells / residential irrigation (new service) | $50 | Same source, option BB |
| Permit Renewal (expiration no more than 30 days) | $60 | Same source, option CC |
| Requested Inspection, per hour | $60 (plus $30 per additional 30 min. or fraction thereof beyond one hour, plus travel time) | Same source, option DD |
Plumbing Permit
VerifiedPlumbing work in unincorporated Yellowstone County is permitted directly by the Montana Building Codes Bureau under Title 50, Chapter 60, Section 505, MCA and ARM 24.301.301/24.301.361, since the county is not a certified local plumbing-code jurisdiction. A per-fixture fee schedule applies. Homeowners performing their own plumbing on their own owner-occupied, non-rental residence are exempt from needing a permit.
Verified 2026-07-02 · Source
Requirements
- Any installation, removal, alteration, or repair of plumbing/drainage systems by a business, trade, or contractor requires a state plumbing permit
- Exemption: homeowners doing their own plumbing installation on a residence for their own personal use (not built on speculation of resale and not intended as a rental) do not need a permit
- Farms, ranches, mines, mills, smelters, railroads, and public utilities are exempt from state plumbing permit requirements
- 2021 Uniform Plumbing Code fixture table (ARM 24.301.351) governs minimum required fixtures
Required documents
- RequiredApplication for Plumbing Permit (BCP-1)Signed by the Master Plumber performing the work (license number required) unless the owner-occupant exemption applies; filed with the Building Codes Bureau, PO Box 200517, Helena, MT 59620-0517, or online at aca-prod.accela.com/bcb
Fee schedule
| Fee type | Amount | Notes |
|---|---|---|
| Each plumbing fixture or trap | $10 per fixture | Montana Building Codes Bureau, Application for Plumbing Permit (ARM 24.301.301/24.301.361, Rev. 11/25) — covers bath tub, lavatory, shower, water closet, kitchen sink, dishwasher, etc. |
| Each new water heater or replacement | $25 | Same source, verbatim fee line item |
| Each connection of building water supply to water service/public utility or private well | $20 | Same source |
| Each connection of building drain to sewer system/public or septic | $20 | Same source |
| Gray water system (commercial or residential) | $60 | Same source |
| Repair or alteration of drainage or vent piping | $30 | Same source |
| Alteration or repair of water piping and/or treatment | $30 | Same source |
| Each storm drain and storm drainage | $30 | Same source |
| Each lawn sprinkler, fire protection system, meter, or backflow device | $30 | Same source |
| Each hose bibb, vacuum breaker, and/or backflow device | $6 | Same source |
| Each industrial water pre-treatment equipment (incl. drainage/vent) | $30 | Same source |
| Medical gas piping systems (per type) | $100 | Same source; additional $10 per outlet over 20 total outlets |
Mechanical / HVAC Permit
VerifiedHVAC, furnace, gas piping, and other mechanical work in unincorporated Yellowstone County requires a State Mechanical Permit from the Montana Building Codes Bureau under Title 50, Chapter 60, Section 104, MCA and ARM 24.301.172, since the county is not a certified local mechanical-code jurisdiction. The fee is calculated from the total cost of the mechanical system installed.
Verified 2026-07-02 · Source
Requirements
- Required for forced air furnaces, air handling units, ventilation systems, refrigeration/cooling equipment, gas piping of any type, mechanical exhaust systems, and similar mechanical work
- State mechanical permits apply on all buildings to which state building permits are applicable, and in areas located outside cities certified to issue their own mechanical permits (unincorporated Yellowstone County qualifies)
- Permit fee is based on total cost of the mechanical system being installed
Required documents
- RequiredApplication for Mechanical Permit (BCP-1)Signed by the mechanical contractor performing the work; filed with the Building Codes Bureau, PO Box 200517, Helena, MT 59620-0517, or online at aca-prod.accela.com/bcb. Requires 17-digit geocode, parcel number, and section/township/range.
Fee schedule
| Fee type | Amount | Notes |
|---|---|---|
| Mechanical system cost $0–$10,000 | $48 for the first $1,000 + $14 for each additional $1,000 or fraction thereof | Montana Building Codes Bureau, Application for Mechanical Permit (ARM 24.301.172, Rev. 11/25) — verbatim fee schedule. Example given: a $9,460 project = $48 + (9 × $14) = $174 total. |
| Mechanical system cost $10,001–$50,000 | $166 for the first $10,000 + $9 for each additional $1,000 or fraction thereof | Same source |
| Mechanical system cost $50,001 or more | $514 for the first $50,000 + $6 for each additional $1,000 or fraction thereof | Same source |
Roofing Permit (Reroof)
VerifiedReroofing is listed as a 'Type of Work' option (Reroof) on the Montana state Application for Building Permit. Because most single-family and up-to-fourplex residential structures are exempt from the state building permit requirement in Montana (private homes/apartments with four or fewer units not serving transient guests), a straightforward residential re-roof on an exempt dwelling generally does NOT require a state building permit. Confirm applicability with the Building Codes Bureau for your specific structure.
Verified 2026-07-02 · Source
Requirements
- Reroofing on an exempt residential structure (4 or fewer units, non-transient) generally does not require a state building permit
- Reroofing on a non-exempt structure (5+ unit residential, commercial, or other non-exempt building) requires a state Building Permit with 'Reroof' selected as the Type of Work
- Confirm with the Building Codes Bureau at (406) 841-2056 whether your specific reroof project requires a permit
Required documents
- OptionalApplication for Building Permit (BCP-1) — ReroofOnly required for non-exempt structures; 'Reroof' is a checkbox under Type of Work on the standard state Building Permit application
Fee schedule
| Fee type | Amount | Notes |
|---|---|---|
| State Building Permit Fee (if applicable) | Calculated based on project valuation; contact Building Codes Bureau at (406) 841-2056 for current fee table | Only applies to non-exempt structures; most residential re-roofs on 1-4 unit dwellings are exempt from the state building permit entirely |
Solar Panel Permit
VerifiedSolar installations in unincorporated Yellowstone County are permitted through the Montana Building Codes Bureau's electrical/alternative-energy permitting track — there is no separate 'solar permit'; instead, the permit type depends on who performs the installation and whether it is grid-tied. The Bureau publishes a specific solar permitting decision flow for new residential construction.
Verified 2026-07-02 · Source
Requirements
- If the installer is a licensed electrical contractor: the contractor applies for a Residential (or Commercial) Electrical Permit for the dwelling/amperage and selects 'solar' on the application
- If the installer is not an electrician: the solar installer submits an Application for Alternative Energy Permit and provides solar system information
- If grid-tied, a Montana-licensed electrical contractor is required to perform the final connection to the utility grid, even if a homeowner or non-electrician installer did the rest
- A homeowner may self-install using a Homeowner Electrical Permit (option H, single family interior/exterior wire) and provide solar information, but a licensed electrical contractor must still make the grid-tie connection if applicable
- Commercial solar always requires a licensed electrical contractor; fee is based on total value of the electrical work including solar
Required documents
- OptionalApplication for Alternative Energy PermitUsed when the solar installer is not a licensed electrical contractor; filed with the Building Codes Bureau, PO Box 200517, Helena, MT 59620-0517, or online. Requires answering: alternative energy type (solar/wind/hydro), solar system type (PV string, generator, or microinverter/AC module), whether the system produces 90+ volts, and whether it is grid-tied.
- OptionalApplication for Residential Electrical Permit or Homeowner Electrical PermitUsed instead of the Alternative Energy Permit when a licensed electrical contractor or the homeowner personally performs the entire installation
Fee schedule
| Fee type | Amount | Notes |
|---|---|---|
| Residential Change of Service (solar connection) | $45 | Montana Building Codes Bureau, Application for Alternative Energy Permit (ARM 24.301.431, Rev. 11/25), option F |
| Commercial solar/electrical project $0–$1,000 | $45 for the first $500 + 6% of the balance | Same source, option G fee chart |
| Commercial solar/electrical project $1,001–$10,000 | $75 for the first $1,000 + 2% of the balance | Same source |
| Commercial solar/electrical project $10,001–$50,000 | $255 for the first $10,000 + 0.5% of the balance | Same source |
| Commercial solar/electrical project $50,001 or more | $455 for the first $50,000 + 0.3% of the balance | Same source |
Accessory Dwelling Unit (ADU)
VerifiedMontana has no ADU-specific state permit type; an ADU in unincorporated Yellowstone County is permitted the same way as any other residential structure. Because the state building-permit exemption applies to 'private homes and apartments with four or fewer units,' a detached or internal ADU that brings the total unit count on the property to four or fewer generally does not require a state building permit for the structure itself — but its electrical, plumbing, and mechanical systems each require their own state permits regardless.
Verified 2026-07-02 · Source
Requirements
- No separate state ADU building permit exists; the standard residential building-permit exemption (four or fewer dwelling units, non-transient) determines whether a structural permit is needed
- Electrical, plumbing, and mechanical permits are required for ADU systems (wiring, water heater, kitchen/bath plumbing, HVAC) regardless of the building-permit exemption
- Zoning compliance for adding a dwelling unit is a SEPARATE matter from building permits — contact Yellowstone County/City-County Planning Division at (406) 247-8247 to confirm zoning allows an ADU on the property before building
- Septic/well capacity for the added unit must be confirmed with Riverstone Health Environmental Health Services at (406) 256-2770
Required documents
- RequiredApplication for Electrical PermitRequired for ADU wiring — see Electrical Permit entry for fee schedule
- OptionalApplication for Plumbing PermitRequired if the ADU has its own kitchen/bath plumbing — see Plumbing Permit entry for per-fixture fees
- OptionalApplication for Mechanical PermitRequired if the ADU has its own HVAC/furnace system
Fee schedule
| Fee type | Amount | Notes |
|---|
Water Heater Permit
VerifiedInstalling or replacing a water heater in unincorporated Yellowstone County requires a state plumbing permit line item from the Montana Building Codes Bureau, unless the owner-occupant exemption applies (homeowner doing the work themselves on their own non-rental, non-speculative residence).
Verified 2026-07-02 · Source
Requirements
- New water heater installation or replacement by a licensed plumber requires a state Plumbing Permit
- Exempt if the owner-occupant is performing the installation themselves on their own personal residence (not a rental, not built for resale)
Required documents
- RequiredApplication for Plumbing Permit (BCP-1)Signed by the Master Plumber performing the work, listing 'Each new water heater or replacement' as a line item
Fee schedule
| Fee type | Amount | Notes |
|---|---|---|
| Each new water heater or replacement | $25 | Montana Building Codes Bureau, Application for Plumbing Permit (ARM 24.301.301/24.301.361, Rev. 11/25) — flat per-unit line item |
Sources & verification
Verified against official sources. Last reviewed 2026-07-02.
Applications & forms
Online permit portal
Department & other records
Fees, timelines, and adopted codes are researched from each jurisdiction's published records — see how we verify. Requirements change and vary by project, so always confirm the current details with the Unincorporated Yellowstone County building department before you submit. PermitBase is an independent reference and is not affiliated with any government agency.