Seventeen states offer tax incentives to people who donate a kidney, a portion of their liver or bone marrow for transplantation. Researchers looked at what happened in the years before and after these tax incentives were passed and found no increase in organ donation rates. A recent NPR-Thomson Reuters Health Poll found that 60 percent of Americans support some kind of financial incentive to organ donors that could be applied to healthcare needs. But the new report raises a caution about how much to expect from financial incentives. But there may be other reasons why the tax breaks aren't working, they say. For one thing, they may just be too small.