To paraphrase the old saying about horses and water, you can give a corporation money, but you can’t make it spend.Thanks to record profits, essentially zero short-term borrowing costs and extremely low effective tax rates, U.S. companies are sitting on over a trillion dollars in cash. Further business tax breaks — while deepening our nation’s fiscal crisis — will do nothing to provide the real incentive companies need in order to invest in our economy: strong consumer demand.Claims that federal business taxes are too high usually cite the nominal corporate tax rate of 35 percent. But what really matters is not the official rate, but how much companies actually pay, and by that measure corporate taxes are already very low.A study released in 2011 by Citizens for Tax Justice of 280 Fortune 500 companies found that their average effective tax rate over the previous two years was just 17.3 percent, less than half the statuary rate.More than one in 10 of these profitable companies paid no federal corporate taxes at all over that period, and some actually got money back from the government.How do companies get away with paying less than the official rate?