As a result of its open seating policy, Southwest Airlines does not allocate seats in advance. Instead, boarding group and position assigned at check-in are used by customers to choose their seats during boarding. Southwest Airlines Seat Selection Policy check-in time determines boarding groups and positions; early check-in gives you a better chance to get your desired seats. For a small additional charge, Southwest allows travelers to check in 36 hours before to takeoff. To guarantee they can seat together, families with children six years of age or younger can board after Group A. Priority is given to those who arrive first when selecting seats.