The maximum stay permitted on a round-trip ticket is generally one year (12 months) from the date of the outbound flight. Most commercial airlines set their booking systems to allow return flights up to 330 to 365 days in advance. However, the "validity" of your specific ticket depends on the fare rules associated with your purchase. Budget-friendly or "non-refundable" tickets often have shorter maximum stay requirements, such as 30, 60, or 90 days. Conversely, full-fare flexible tickets almost always allow for a full year. It is also critical to distinguish between the airline ticket's validity and your legal visa requirements. Even if your ticket allows you to return in 12 months, your visa or visa-waiver (like the ESTA or Schengen rules) may only allow you to stay in a country for 90 days. Always ensure that your return date aligns with both your airline's fare rules and the immigration laws of your destination to avoid being denied boarding or facing fines upon your return.