### Question
How is the term cost proportion defined?


### Answer
The term **cost proportion** is defined in *42 U.S.C. § 1395l* as the following:

> 75 percent for cost reporting periods beginning in fiscal year 1988, 50 percent for portions of cost reporting periods beginning on or after October 1, 1988, and ending on or before December 31, 1990, and 42 percent for portions of cost reporting periods beginning on or after January 1, 1991

#### Citation:
  - *42 U.S.C. § 1395l*
  - Heading: **CHAPTER 7-SOCIAL SECURITY > SUBCHAPTER XVIII-HEALTH INSURANCE FOR AGED AND DISABLED > Part B-Supplementary Medical Insurance Benefits for Aged and Disabled**

