The Program
Since 2018, the IRS certifies seriously delinquent tax debt to the State Department, which can deny or revoke passports. The threshold is adjusted annually for inflation.
The Exemptions
Debts in installment agreements, CNC status, pending OICs, or pending CDP hearings are exempt. Enter any of these statuses and the certification is reversed within 30 days.
Your passport is at risk only if you are doing nothing about your tax debt. Any active resolution effort protects it.