US taxpayers residing abroad questioned at US border regarding back taxes

U.S. Taxpayers traveling to the United States with unpaid U.S. tax assessments can be detained at the border, questioned, and flagged for follow-up enforcement. If a taxpayer has an unpaid tax liability and is subject to a resulting Notice of Federal Tax Lien, the IRS may submit identifying taxpayer information to the Treasury Enforcement Communications System (TECS), a database maintained by the Department of Homeland Security (DHS).