https://www.noridianmedicare.com/parta/claims/timely/ppaca_timely_sub_nas_summary.pdf

The Patient Protection and Affordable Care Act (PPACA), Section 6404, has reduced the maximum period for timely submission of Medicare claims to not more than 12 months beginning with dates of service on or after January 1, 2010.

Medicare Timely Claim Submission Defined in PPACA