For international private jet travel, a valid passport is absolutely mandatory for every passenger on board, including children and infants. Even though you bypass the commercial terminal, you are still crossing a sovereign border, and your manifest is shared with government customs and immigration agencies. Upon arrival at a private terminal (FBO), you will still be met by an immigration officer who will physically inspect and stamp your passport. However, for domestic private flights within the same country, a passport is usually not required. In the U.S. in 2026, you simply need a REAL ID-compliant government photo ID, such as a driver's license. The "private" aspect allows for a much faster screening process—often taking only seconds—but it does not exempt travelers from the federal and international laws that require proof of citizenship and identity when moving between nations.