Norway, Tesla Inc.’s (TSLA) third biggest auto market, is mulling a new tax on electric vehicles (EV).

The Norwegian government’s proposed 2018 budget, published on Thursday, contains information about a new tax on heavier emission-free vehicles, reported Business Insider. Electrek identified Tesla as one the biggest potential victims of the change as the company tends to use bigger battery packs to provide greater range.

If passed, Tesla’s 5,531-pound Model X P100D could be taxed at 70,000 kroner ($9,000). Lighter vehicles, meanwhile, including Tesla’s 4,608-pound Model S 75D, are expected to be taxed at 7,000 kroner ($900 USD), reported local news outlet VG earlier. (See also: Automakers Will Get a Jolt From Electric Car Sales.)

The country previously said it wanted all new cars to be all-electric by 2025. At present, it is believed that just under half of new vehicles in the country meet this criterion. According to Business Insider, Hans Andreas Limi from the political party Fremskrittspartiet said the fee is being considered because heavy EVs take a toll on roads.

Despite its small population — Norway is home to just 5.2 million people — a new tax could have an impact on Tesla’s top-line. Norway is the leading country for EV adoption per capita, according to Electrek, and Tesla’s third biggest market. The popularity of EVs in Norway has mainly been attributed to government incentives.

“Norway’s electric vehicle boom has been built on generous government incentives. EVs are exempt from car-purchase taxes and the 25 percent sales tax levied on just about everything else, and they get a break on annual fees,” Sture Portvik, an Oslo city official, previously told CleanTechnica. “Drivers plug in for free at municipal power points, generally don’t pay tolls, and can use bus lanes to avoid traffic. On ferries across Norway’s deep fjords, electrics travel at no cost. It’s no surprise, then, that Norwegians call gasoline-powered vehicles fossilbilerfossil cars.” (See also: Tesla May Miss Its iPhone Moment: Barclays.)

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