Six Massachusetts hospitals are suing the state, saying they were shortchanged by the 2006 health care law.
The hospitals claim the state violated a law requiring health care providers be adequately reimbursed for caring for Medicaid and Medicare patients.
The six are known as "disproportionate share hospitals" because at least 63 percent of their patients are covered by public insurance.
A spokesman for the Executive Office of Health and Human Services said the state recently increased payments to the hospitals by 10 percent and is complying with the law.
The hospitals include the Berkshire Medical Center, Signature Healthcare Brockton Hospital, Cape Cod Hospital, Holyoke Medical Center, Merrimack Valley Hospital and Quincy Medical Center.
The lawsuit will be filed Tuesday.
In July, Boston Medical Center filed a lawsuit claiming the state illegally cut payments for treating low-income patients.