Legal Definitions - home-port doctrine

The home-port doctrine is a principle in maritime law that clarifies where a commercial vessel can be taxed. It establishes that a ship engaged in trade or transportation across state lines or international borders is subject to property taxes only in its designated home port. This home port is typically the location where the vessel is officially registered. The primary purpose of this doctrine is to prevent multiple jurisdictions from taxing the same vessel, thereby ensuring a single, clear taxing authority.

Here are a few examples to illustrate the application of the home-port doctrine:

• International Cargo Ship: Imagine "The Ocean Voyager," a massive container ship owned by a shipping company based in Seattle, Washington. This vessel is officially registered in Seattle and regularly transports goods between ports in the United States, Japan, and Germany. Even though "The Ocean Voyager" spends significant time docked in foreign ports like Yokohama or Hamburg, or other U.S. ports like Los Angeles, under the home-port doctrine, only the state of Washington (specifically, the jurisdiction of its home port in Seattle) has the authority to levy property taxes on the vessel. Other states or countries where it temporarily docks cannot impose their own property taxes on the ship.
• Interstate Tugboat Fleet: Consider "Riverbend Towing," a company operating a fleet of tugboats that regularly assist barges and other vessels along the Mississippi River, navigating through multiple states such as Louisiana, Mississippi, and Arkansas. All of Riverbend Towing's tugboats are registered in New Orleans, Louisiana. Despite these tugboats frequently operating and docking in ports within Mississippi or Arkansas, the home-port doctrine dictates that only Louisiana, as the state of their registered home port (New Orleans), can impose property taxes on the Riverbend Towing fleet. Neither Mississippi nor Arkansas can levy property taxes on these vessels because their home port is in another state.