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On vehicles required to be registered in Montana, material on the front side windows must have light transmission of 24% or more and luminous reflectance of 35% or less. Behind the front seat the floor is 14%, with the same reflectance cap, except on multipurpose vehicles, vans and buses. Windshield material must be clear below the AS-1 line and not red, yellow or amber above it. No tolerance is stated.
Source: Mont. Code Ann. § 61-9-405; Mont. Code Ann. § 61-9-428 (waiver, including medical reasons); Mont. Code Ann. § 61-9-429 (window tinting penalty); Mont. Code Ann. § 46-18-212 (sentence when no penalty is specified). Summary last checked against these sources on September 28, 2026.
| Window | Rule |
|---|---|
| Windshield | Sunscreening material on the windshield must be clear and transparent below the AS-1 line, and material above the AS-1 line may not be red, yellow or amber (61-9-405(4)(a)). The section states no inch figure and no light-transmission percentage for the windshield. |
| Front side windows | Sunscreening or other transparent material on the front side windows may not have a luminous reflectance of more than 35% or a light transmission of less than 24% ((4)(b)). Light transmission is the ratio of the total light passing through the sunscreening or transparent material to the total light falling on the window ((5)(b)). The section states no measurement tolerance. |
| Rear side windows | Side windows behind the front seat may not have sunscreening or other transparent material with a luminous reflectance of more than 35% or a light transmission of less than 14% ((4)(c)). This limit does not apply to the side windows behind the front seat on a multipurpose vehicle, van or bus ((4)(c)). |
| Rear window | The same 14% light-transmission floor and 35% reflectance cap apply to the rear window ((4)(c)), except on a multipurpose vehicle, van or bus ((4)(c)). |
| Reflectance and color | Luminous reflectance of more than 35% is barred on the front side windows and on the windows behind the front seat ((4)(b), (4)(c)); luminous reflectance is the ratio of the total light the material reflects outward to the total light falling on the window ((5)(c)). Red, yellow or amber sunscreening material is barred above the windshield's AS-1 line ((4)(a)). |
| Installers | A person who applies sunscreening material or glass-plastic glazing material in a manner that results in a vehicle having a window that violates 61-9-405(4) is guilty of a misdemeanor (61-9-429(2)). No installer sticker or label requirement was found in the sections read. |
VLT (visible light transmission) is the percentage of visible light that passes through a window or film; a higher number means lighter tint. Most state limits are measured on the finished window (glass and film together). Where a rule is stated for the film itself, the table says so. Some states also limit reflectance, the share of light bounced back off the surface (a mirror-like look).
Subsection (4) covers motor vehicles required to be registered in Montana when operated on a highway ((4)), and it applies to all vehicles equipped with tinted windows, including windows with less than 100% light transmission to which additional sunscreening material has been applied ((6)). Sunscreening material means a film, material, tint or device applied to vehicle windows to reduce the effects of the sun ((5)(g)). Subsection (4) does not apply to a multipurpose vehicle with tinted windows installed by the manufacturer, or to a hearse, ambulance, government vehicle, or any vehicle with a currently valid certificate of waiver affixed ((7)). The 14% limit behind the front seat does not reach multipurpose vehicles, vans or buses ((4)(c)); the section does not name SUVs or pickups, and it defines a multipurpose vehicle as one designed to carry 10 or fewer passengers that is constructed on a truck chassis or with special features for occasional off-road use ((5)(d)). The windows of a camper, motor home, pickup cover, slide-in camper or other motor vehicle must meet the federal safety glazing standard in 49 CFR 571.205 ((4)(d)).
The highway patrol or a local law enforcement agency may grant a waiver of the 61-9-405(4) standards for reasons of safety or security or for medical reasons based on an affidavit signed by a licensed physician, licensed physician assistant or advanced practice registered nurse (61-9-428); the text does not make clear whether the affidavit is required only for medical reasons. The waiver must be in writing and must identify the vehicle, the date issued, the owner, the reason for the waiver and the dates it is effective (61-9-428). Subsection (4) does not apply to a vehicle with a currently valid certificate of waiver affixed (61-9-405(7)). The department must issue a certificate of waiver for a vehicle registered in Montana on October 1, 1991, that was then equipped with material prohibited under subsection (4) ((7)).
A person who owns or operates a motor vehicle in violation of 61-9-405(4) is guilty of a misdemeanor, and so is a person who applies sunscreening or glass-plastic glazing material in a manner that results in a window that violates it (61-9-429(1), (2)). Both are punishable under 46-18-212, which allows up to 6 months in the county jail, a fine of up to $500, or both, when no other penalty is provided.
On vehicles required to be registered in Montana, sunscreening or other transparent material on the front side windows may not have a light transmission of less than 24% or a luminous reflectance of more than 35% (Mont. Code Ann. 61-9-405(4)(b)). On the rear window and side windows behind the front seat the floor is 14%, with the same 35% reflectance cap, except on a multipurpose vehicle, van or bus ((4)(c)). The section states no measurement tolerance.
The 14% limit on the rear window and side windows behind the front seat does not apply to a multipurpose vehicle, van or bus ((4)(c)). The statute does not name SUVs or pickups; it defines a multipurpose vehicle as one designed to carry 10 or fewer passengers that is constructed on a truck chassis or with special features for occasional off-road use ((5)(d)). The front side window limits in (4)(b) still apply to these vehicles. Subsection (4) does not apply at all to a multipurpose vehicle whose tinted windows were installed by the manufacturer ((7)).
Reflectance is capped rather than banned: material on the front side windows, and on the rear window and side windows behind the front seat, may not have a luminous reflectance of more than 35% ((4)(b), (4)(c)). Red, yellow or amber sunscreening material is not allowed above the windshield's AS-1 line ((4)(a)).
Only in a limited way. Sunscreening material on the windshield must be clear and transparent below the AS-1 line, and material above the AS-1 line may not be red, yellow or amber (61-9-405(4)(a)). The statute gives no inch figure or percentage for the windshield.
Yes, by waiver. The highway patrol or a local law enforcement agency may grant a written waiver of the 61-9-405(4) standards for medical reasons based on an affidavit signed by a licensed physician, licensed physician assistant or advanced practice registered nurse (61-9-428). Subsection (4) does not apply to a vehicle with a currently valid certificate of waiver affixed (61-9-405(7)).
No installer sticker or label requirement was found in 61-9-405, 61-9-428 or 61-9-429. The only item the section describes as affixed to a vehicle is a certificate of waiver (61-9-405(7)).
Owning or operating a vehicle that violates 61-9-405(4) is a misdemeanor, and so is applying sunscreening or glass-plastic glazing material in a manner that results in a violating window (61-9-429). Under 46-18-212 a misdemeanor with no other penalty provided is punishable by up to 6 months in the county jail, a fine of up to $500, or both.
Running a tint shop in Montana? See shop software for Montana.
This page summarizes Montana statute and regulation text for general information and is not legal advice. It covers passenger vehicles with aftermarket film (film added after the vehicle left the factory) and includes SUV, van and truck rules where the state sets different ones. Some vehicle types, such as limousines, buses, commercial and law-enforcement vehicles, and factory glass are treated differently in some states, and whether a vehicle registered in another state is covered depends on the state; see “Who this covers” above. Federal glazing rules (FMVSS 205, 49 CFR 571.205) apply separately from state law, and 49 U.S.C. 30122 bars manufacturers, distributors, dealers, rental companies and motor vehicle repair businesses from knowingly making inoperative any part of a device or element of design installed to comply with a federal motor vehicle safety standard, so installers should check both. Laws change and enforcement varies; confirm current requirements with the state before tinting. Before tinting, ask the installer to measure your glass and confirm the finished window will meet the limit; afterward, ask for a reading on a light-transmission meter and keep it.