Colorado lawmakers are considering a new tactic to go after tax revenue from online sales. They want out-of-state online retailers to either start collecting the tax or send annual notices to their customers telling them to pay the tax themselves, the Associated Press reports. The proposal, which was set to be debated Monday in the full Senate, is part of an overall package of tax bills to cover a $1.5 billion shortfall due to the recession. The amended measure (House Bill 1193) would require retailers like Amazon.com Inc. and Overstock.com Inc. to either start collecting sales tax on March 1 or send notices to their customers stating how much they spent with them in the previous year and telling them how much they owe in state sales tax.