Many countries require your passport to be valid for at least . If your passport expires sooner than this window, you may be denied boarding by your airline or entry by border officials.
For U.S. Lawful Permanent Residents (Green Card holders), the "6 month rule" refers to travel outside the United States. 6 Month Rule
Some regions, like the Schengen Area , generally require only three months of validity beyond your planned departure date. Permanent Residency (Immigration) Many countries require your passport to be valid
The "6 Month Rule" most commonly refers to for international travel, but it also appears in contexts like residency and medical procedures. Passport Validity (Travel) like the Schengen Area