On September 16, the state of Colorado will force a suspension of taxes on recreational cannabis. Officials say it could cost the state, and equally save taxpayers, $3–$4 million.

Colorado’s Taxpayer’s Bill of Rights not only requires voter approval for new taxes, but says that any new taxes should be waived and refunded if the overall collection amount exceeds projections given to voters when they first approved the new taxes. Because overall tax collection in 2014 exceeded projections, Colorado lawmakers had to decide how to refund voters their money. Their solution was a one-day tax waiver.

“At first I was in disbelief we were doing this,” said Denver area dispensary owner Cheri Hackett. “Once our lawyer said, ‘No, we really are doing this,’ we started getting ready. We’re thinking there will be huge crowds.”

Colorado has 380 recreational dispensaries and 480 licensed recreational cannabis growers — up from a few dozen in the state’s first months of legalization.