The ads promoting a November ballot measure to legalize sports betting in Missouri tout the potential for millions of new tax dollars devoted to schools. If voters approve the measure, it’s a good bet they will see even more ads offering special promotions for bettors.

Many of those promotional costs — in which sportsbooks provide cash-like credits for customers to place bets — will be exempt from state taxes, effectively limiting the new revenue for education.

The Missouri ballot measure highlights an emerging debate among policymakers over how to tax the rapidly growing industry, which has spread from one state — Nevada — to 38 states and Washington, D.C., since the U.S. Supreme Court opened the door to legalized sports wagering in 2018.