Norway is likely the friendliest place on Earth for electric cars.

The government's generous incentives and perks have led to an electric-car boom, and the country is now Silicon Valley automaker Tesla's third-largest market.

However, Norway's latest taxation proposal could have serious implications for Tesla in the near future.

DON'T MISS: Half of Norway's new-car sales are now hybrids or electrics

Norway's proposed 2018 budget includes a new tax on heavier "emission-free" vehicles to compensate for the toll heftier electric cars take on the country's roads.

The tax could levy an additional $9,000 on vehicles considered "heavy" by the Norwegian government, according to Business Insider.

Specifically, the Tesla Model X P100D would fall into the taxation category with a 5,531-pound curb weight.

2017 Tesla Model X

2017 Tesla Model X

Tesla tends to use larger, and subsequently heavier, battery packs to squeeze longer ranges from its more premium cars.

The Model X P100D could be a rare case since the proposed budget calls for only a $900 tax on lighter emission-free cars, such as the Tesla Model S 75D, which weighs 4,608 pounds.

Still, an extra $9,000 on top of a Model X P100D's sale price would likely sway potential buyers into more affordable electric cars, potentially from rival automakers.

READ THIS: Mercedes EQC electric SUV reservations open in Norway, for 2019 delivery

As of this year, half of Norway's new-car sales were hybrid or electric cars and the Tesla Model S was one of the top-selling cars in the country.

The potential tax is actually a smidge ironic since Norway's love affair with electric cars is largely due to the government exempting them from various taxes gasoline- and diesel-powered car owners must pay.

Specifically, electric cars are exempt from all current vehicle taxes and the country does not levy its 25-percent sales tax on them, either.

2017 Tesla Model X

2017 Tesla Model X

Owners of electric cars also receive perks such as free charging, free parking, and access to restricted bus lanes in urban areas.

Norway plans to aggressively phase out fossil-fuel-powered cars in the coming years.

CHECK OUT: Norway's Goal: All New Cars Will Be Emission-Free By 2025 To Cut Carbon

It was one of the first countries to announce a ban on new cars powered by gasoline or diesel; Norway's plan will execute said ban by 2025.

The Netherlands followed suit with its own ban with an identical timetable. France and the United Kingdom announced similar actions, though both countries target 2040 to phase out fossil-fuel vehicles.

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