What appears to be a floating home in Miami’s Biscayne Bay, isn’t actually a house. At least that’s how lawyers representing the millionaire that owns it argues. County officials are trying to hit the houseboat with a property tax bill, however to the county, it’s not an actual boat.

reports that the houseboat in question, or whatever it is, is known as the Arkup #1. It’s manufactured by a company with the that specializes in what they call “livable yachts” and floating islands. The company’s founders, who built the #1, see it as a solution to climate change, among other things:

The Arkup #1 was built in Miami by Nicolas Derouin and Arnaud Luguet, two French engineers who live in South Florida and dedicated themselves to renewable energy and environmental preservation amid the threat of climate change and sea-level rise.

It is environmentally friendly, featuring things like a rainwater collection system and solar panels. It was purchased by British businessman Jonathan Brown’s company MacKnight International for $3.3 million in 2021. Despite floating in the bay since Brown’s purchase, Miami-Dade County officials have decided to label the Arkup #1 a “floating structure.” The result is a property tax bill of $120,000.

But Brown’s lawyers argue that the house is registered as a ship with the U.S. Coast Guard. Brown and his legal team have now filed suit against the county.

We believe the sole reason our client is in this position — an unconstitutional tax assessment — is because of the shape and the style and the look of this boat,” said attorney Ivan Abrams, who represents the boat’s owner, MacKnight International Inc. “If it were designed like any other yacht, we don’t think we’d be in this position.

As I’m sure you have noticed and as our own Ryan Erik King pointed out, the Arkup barely meets seaworthiness requirements: it can travel up to five knots (5.75 mph) per hour, has a bow deck with controls for navigation, and has small 136 horsepower thrusters and an anchor system. It honestly comes across as a loophole for rich people to live on the water and not pay property taxes.

A spokesperson confirmed that the Arkup is the only “floating structure” being hit with a tax bill, something the owner’s lawyers are saying is a slippery slope:

If this boat is a floating structure, that means all the other yachts docked around Palm Island and Star Island that are not used every single day to go cruising are subject to taxation.

But county officials aren’t buying it saying that the Arkup “was not built to be primarily used as a means of transportation over water.” So it looks like the Arkup may not be a boat after all.