The phrase "transitional arrangements" refers to temporary plans or agreements that are put in place to help move from one situation to another. It is a way to smoothly transition or adjust to a new state or set of rules. Full definition
A major part of the proposals involves the introduction of transitional arrangements which are over complex and too rigid. (newlawjournal.co.uk)
The threshold will replace transitional arrangements which saw free meals offered to all pupils from universal credit - claiming households. (schoolsweek.co.uk)
The question of identifying acquired rights, and providing transitional arrangements, would also arise in connection with the business activities of companies and firms. (blog.politics.ox.ac.uk)