In 2010, the Internal Revenue Service (IRS) announced the requirement to disclose uncertain tax positions (UTPs) on a new schedule (Schedule UTP) to be filed with federal corporate income tax returns. Schedule UTP requires companies to report line-item detail to the IRS of the aggregate disclosure requirement of uncertain tax benefits (UTBs) established by FIN 48 (KPMG 2010a). I examine firms’ change in reporting UTBs subsequent to the announcement of Schedule UTP. Overall, the results indicate firms reduce not only the levels of reported UTB, but they also significantly reduced the year to year changes in reported UTBs. Consistent with my predictions, firms which are required to file Schedule UTP earlier have an incrementally more significant reduction in reported UTBs. Results provide mixed evidence for financially conservative firms. Contrary to expectations, the decrease in reported UTBs is not incrementally more significant for firms in the upper quartile of tax aggressiveness. Additionally, I examine whether the announcement of Schedule UTP impacts other proxies for tax aggressive behavior. Results indicate that book-tax differences decrease subsequent to Schedule UTP. However, neither measure of tax aggressiveness based on effective tax rates provides statistically significant results. This finding suggests the decrease in reported UTBs is merely a change in reporting behavior and not a change in aggressive tax behavior.