What is a T driving license?

With a T-category driving license you can drive:

Tractors, except for T3b tractor-aTVs mentioned in category AM121, with a maximum design speed of up to 60 kilometres per hour, as well as motorized construction machinery and snowmobiles with their attached towed vehicles.

• Vehicles of categories T1a and T1b, T2a and T2b and T3a

Tractors with a maximum design speed exceeding 60 km/h require a passenger car or truck driving license, depending on the mass of the vehicle.

T licence = tractor licence and AM121 licence = light quadricycle licence. This means that there is no separate all-terrain vehicle licence.

The required driving license category depends on the category of the all-terrain vehicle or tractor displayed on the registration certificate. For a snowmobile, you always need a category T license. https://cap.fi/en/courses/all-terrain-vehicle-tractor-snowmobile/