Tiffany's bill would impose a tax on mining companies' revenue, giving 60 percent of the money to local governments and 40 percent to the state after the locals are compensated for mining impacts.Democrats contend the tax might not generate anything if Gogebic Taconite has a down year. The tax doesn't kick in until a company makes at least $536,600, and companies are allowed to deduct operational costs. Democrats say the tonnage tax is guaranteed money if the company extracts anything. The fiscal bureau prepared the estimates for the Legislature's budget committee, which is scheduled to vote Monday on the bill. Approval would clear the way for a full vote in the Senate and Assembly. Passage is all but certain. Republicans control both legislative houses and Republican Gov. Scott Walker has touted the mining bill as the GOP's signature job creation plan.