SANTA FE, N.M. — A standoff over millions of dollars in insurance premium taxes escalated on Tuesday between New Mexico’s attorney general and the state’s largest health-care insurance provider.

New Mexico Attorney General Hector Balderas renewed accusations that a for-profit insurance arm of Presbyterian Healthcare Services used an illegal accounting procedure to avoid paying millions of dollars in taxes and surcharges on insurance premiums.

The insurance subsidiary, Presbyterian Health Plan, denied that it owes the state of New Mexico additional premium taxes in new court filings this week.

It filed a motion Monday to dismiss the attorney general’s lawsuit, explaining that state insurance regulators reviewed and approved the company’s amendments to past tax payments.

“The amended premium taxes in question in this lawsuit have been reviewed, audited, approved and settled by the Office of the Superintendent of Insurance and its predecessor,” Presbyterian stated.

At a news conference in Albuquerque, Balderas urged Presbyterian to pay tax liabilities dating back to 2003 that were circumvented with an “illegal amendment.”

Balderas said his lawsuit was designed to ensure Presbyterian pays its full share of taxes to support the state’s Medicaid system — “especially when we as a state have been investing billions of dollars into the Presbyterian health care delivery system.”

Balderas said the dispute revolves around 2003 and 2004 tax payments by Presbyterian that were revised by the company many years later. New Mexico collects hundreds of millions of dollars each year through a 3 percent tax on insurance premiums and additional surcharges.

“For some reason, under some type of agreement, they thought they could go back and undo the 3 percent they had paid,” he said. “There is no authority in law for a company to go back and change their tax rate.”

He said Presbyterian went back eight years later to revise its tax liabilities when average taxpayers have three years to make amendments.

“More appalling is that these taxes go back into the Medicaid system, which is system (where) we have paid them billions of dollars to fund quality health care in New Mexico,” Balderas said.

In a written statement, Presbyterian Healthcare Services CEO Dale Maxwell said the company honors its tax obligations.

“Our response (to the lawsuit) sets forth facts which show that Presbyterian did not commit fraud against the state of New Mexico,” he said. “We work openly and in good faith with governmental authorities, and we honor our obligations as a New Mexico taxpayer.”

New Mexico has commissioned an audit of insurance premium taxes dating back to 2000 to determine if the state may be owed money by specific companies, with results due out this fall.

A previous sampling of taxes collected between 2010 and 2015 turned up at least $193 million in possible underpayments by major insurance providers. The Office of the Superintendent of Insurance has questioned the reliability of that study.

New Mexico state government is confronting increasing financial obligations to Medicaid health care coverage for poor and disabled residents, as the federal government gradually scales back subsidies for expanded coverage to low-income individuals.