Synthetics Trafficking and Overdose Prevention Act of 2016 or the STOP Act of 2016

This bill amends the Tariff Act of 1930 to make the Postmaster General or Postmaster General designee, including a person holding a valid customs broker's license, the importer of record for non-letter class mail imported into the United States.

The term "non-letter class mail" means any product of the U.S. Postal Service or a Universal Postal Union designated operator that is provided pursuant to:

• the Universal Postal Union's Parcel Post Regulations and Final Protocol; or
• the Universal Postal Union's Letter Post Regulations and Final Protocol, except small letters, as in effect upon enactment of this bill.

The bill amends the Consolidated Omnibus Budget Reconciliation Act of 1985 to impose a duty of $1 on each item of non-letter class mail imported into the United States.

The bill amends the Trade Act of 2002 to direct the Department of the Treasury to require the Postmaster General to provide for the advanced electronic transmission to the U.S. Customs and Border Protection of certain information on non-letter class mail imported into the United States.