One of Delaware’s largest revenue sources could soon take a hit if the U.S. Supreme Court sides with a special master’s finding that official checks issued by MoneyGram qualify as money orders, not third party bank checks.

Upwards of $150 million in unclaimed checks is at stake, and the court’s ruling on argument scheduled to be presented Monday could either keep that money in Delaware, where MoneyGram is incorporated, or redistribute the money to the states where the checks were initially purchased.