Colorado officials spent $453,000 so far in tax dollars fighting for information on how to tax residents’ purchases from out-of-state retailers, but now state constitutional requirements will likely force the Department of Revenue to refund any money it collects.

DOR and the Direct Marketing Association have been in a six-year legal battle over whether out-of-state retailers, like Amazon.com, have to report untaxed purchases so the state can go after residents for that money.

DMA maintains House Bill 10-1193, which imposed the mandate, violates the Commerce Clause and has pushed for the U.S. Supreme Court to hear the case.

“Colorado law treats out-of-state companies and in-state companies differently,” Chris Oswald, DMA’s vice president of advocacy, told Watchdog.org. “It’s a clear violation of the Commerce Clause because the Colorado law imposes notice and reporting requirement for out-of-state companies that it doesn’t impose on in-state companies.”

DMA suffered setbacks in February and March when a three-judge panel in the federal appeals court upheld the law, and the U.S. Supreme Court declined to hear it. But DMA said it will appeal to the full appellate court and, if that fails, try again for a hearing at the nation’s top court.

DOR spokeswoman Lynn Granger said the state couldn’t avoid spending the money because the DMA sued.

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