The GW Hospital is one of 19 hospitals suing the U.S. Department of Health and Human Services for underpaying the centers for various periods between fiscal years 2006 and 2011.

In a 30-page complaint filed Sept. 20, the hospitals claim that the secretary of health and human services, a post that has been filled by Alex Azar since January, violated multiple administrative procedures and Medicare acts by underpaying “disproportionate share hospitals” – centers that serve a significantly disproportionate number of low-income patients.

Congress passed a law in 1985 mandating that the federal government give DSH centers additional funds on top of Medicare payments “in recognition of the relatively higher costs associated with providing services to low-income patients,” the suit states.

The plaintiffs claim the health and human services department improperly calculated their eligibility for DSH payments for several years by including Medicare Part C recipients in the number of inpatients entitled to benefits under Medicare Part A. Part A recipients receive inpatient hospital coverage, while Part C recipients receive their Medicare benefits from a private health plan.

The plaintiffs claim that Part C recipients shouldn’t be counted in Part A numbers because even if they are eligible for Part A benefits, they are not entitled to it if they have a Part C plan. Combining the numbers improperly represented what percentage of low-income patients the hospitals serviced, the complaint alleges.

“The hospitals’ DSH payments at issue are unlawful and should be set aside because they are unsupported by substantial evidence in the record,” the claim states.

The hospitals all claimed various different years of underpayment, but GW Hospital was underpaid for DSH compensation between 2006 and 2011, the suit alleges.

The plaintiffs ask the court to order Azar to recalculate the hospitals’ payments, repay the currently undetermined amounts he owes the hospitals with interest and pay costs produced from the lawsuit.

Caitlin Oakley, a spokeswoman for the U.S. Department of Health and Human Services, declined to comment, citing a policy to not comment on pending litigation. A spokeswoman for The GW Hospital did not return a request for comment and the lawyers suing on behalf of the hospitals declined to comment.

Parth Kotak contributed reporting.