Extending Limits of United States Customs Waters Act of 2023 This bill extends the customs waters territory of the United States. Under current law, customs waters means waters within four leagues of the coast of the United States. This bill revises the definition to include (1) the territorial sea of the United States to the limits permitted by international law in accordance with Presidential Proclamation 5928, dated December 27, 1988, that extended such limits to 12 nautical miles from the baselines of the United States; and (2) the contiguous zone of the United States to the limits permitted by international law in accordance with Presidential Proclamation 7219, dated September 2, 1999, that extended such limits to 24 nautical miles from the baselines of the United States.