As of Monday, crowds of 2000 seated supporters can be accommodated in any ground without express permission. Celtic, Aberdeen and Hibernian have all done that for their impending European qualifiers, and Rangers for Saturday's friendly against Arsenal. Clubs apply directly to their local authority for the increase in capacity. Also, some clubs have restricted availability to those who live locally - ruling out some of their own fans as well as away supporters. For the midweek European games, Aberdeen are selling to season-ticket holders on a first-come, first-served basis, with any remaining tickets on general sale.
Source: BBC July 16, 2021 12:00 UTC