"The Medicare Prescription Drug, Improvement, and Modernization Act of 2003 (MMA; P.L. 108-173) requires the Medicare Board of Trustees to provide in its annual reports an expanded analysis of Medicare expenditures and revenues. Specifically, if the Medicare trustees determine that general revenue funding for Medicare is expected to exceed 45% of Medicare outlays for the current fiscal year or any of the next six fiscal years, a determination of excess general funding is made. If the determination is issued for two consecutive years, a funding warning is issued, which triggers certain presidential and congressional actions related to the introduction and consideration of legislation designed to respond to the warning. […] In each of their 2014 through 2016 reports, the Medicare trustees projected that Medicare general revenue funding would not exceed 45% of total Medicare outlays within seven fiscal years. Therefore, the Medicare trustees did not issue funding warnings in those years, and the President was not required to submit a related legislative proposal subsequent to the release of his FY2016 and FY2017 budgets nor will he be required to submit such legislation subsequent to the submission of his FY2018 budget. The Medicare funding warning focuses attention on the impact of program spending on the federal budget, and it provides one measure of the financial health of the program."
CRS Report for Congress, RS22796
Federation of American Scientists: http://www.fas.org/sgp/crs/index.html