Build the tax checklist before the move creates the facts.
Organize destination-tax, treaty, U.S. federal, and former-state questions in one place. The result is a preparation list—not a residency ruling, eligibility test, or tax calculation.
Your planning checklist
Portugal: treaty + state-residency review
In force. The U.S.–Portugal income-tax treaty can allocate taxing rights and provide relief in defined situations, but it does not switch off ordinary U.S. filing for U.S. citizens.
This tool stores nothing and does not determine residence, treaty eligibility, or tax owed. It is an educational organizer for a conversation with qualified U.S. and destination-country advisers.