55 Pa. Code § 1181.64
Each facility shall submit a cost report to the Department within 90 days following the close of each fiscal year as designated by the facility in accordance with § 1181.71 (relating to annual reporting). The report shall be prepared using the accrual basis of accounting and must cover a fiscal period of 12 consecutive months. Facilities beginning operations during a fiscal period will prepare a report from the date of approval for participation to the end of the facility's fiscal year. The cost report shall identify costs of services, facilities and supplies furnished by organizations related to the provider by common ownership or control.
55 Pa. Code § 1181.64
This section cited in 55 Pa. Code § 1181.45 (relating to ongoing responsibilities of providers); 55 Pa. Code § 1181.52 (relating to payment conditions); and 55 Pa. Code § 1181.91 (relating to failure to file a cost report).