The Colorado Department of Revenue has readopted temporary emergency regulations to require out-of-state retailers that are doing business in Colorado and have substantial nexus with the state to collect Colorado sales or use tax. Out-of-state retailers are considered to have a substantial nexus with Colorado for sales tax purposes if the retailer’s gross revenue from the sale of tangible personal property or services delivered into Colorado exceeds one hundred thousand dollars or the retailer sold tangible personal property or services for delivery into Colorado in two hundred or more separate transactions. The Department has extended out-of-state retailers a grace period until May 31, 2019 to comply.