“It began to change the game significantly,” Mr. Ventrell said. “The money is now there.”

Particularly when profit is part of the equation, he said, pressure to fill beds could lead to unethical efforts to recruit patients. That possibility prompted the treatment providers association to create an ethics code two years ago.

“The addiction industry was no longer a small collegial group that was carefully working together and trying to do the best thing for clients,” Mr. Ventrell said. “Rather, it had become a very competitive business.”

The code specifically addresses remuneration: “No financial rewards or substantive gifts are offered for patient referrals.”

In February, Mr. Ventrell put in place a system for filing complaints about member organizations.

The system is too new and the data too sparse to draw conclusions yet, he said; so far, of the 10 complaints filed, four related to payments for patient referrals.

In New York City, 346 treatment programs — including residential and outpatient — are certified by the New York State Office of Alcoholism and Substance Abuse Services; 22 of them are on Staten Island.

Rob Kent, the general counsel for the agency, said he was concerned about paying for referrals.

“If you are referring a patient to somebody that is paying you, is it because they are paying you or because you believe the program is the best option for the patient?” Mr. Kent said.

Addiction treatment providers across the city also said they had been offered money for referrals.

Donna Mae DePola, the president of the Resource Counseling Center, which offers outpatient treatment in Brooklyn and is opening a recovery center on Staten Island this year, said the subtle nature of the approaches made them hard to document and report to the authorities.