SPRINGFIELD — According to a report from Illinois Public Radio, since November, the state owes businesses in the Vendor Support Initiative program more than $600 million.

IPR says the documents it obtained don’t include the 1 percent interest fee applied per month to bills over 90 days old under the Prompt Payment Act.

The program allows companies to buy invoices of others who have done business with the state, and are awaiting payment.

The companies pay the bills, and then make a profit by collecting both the overdue money and the interest on it when the state eventually pays up.

A spokesman for the state agency that administers the program told IPR the comptroller won’t have the voucher information until the bill is presented for payment.

It’s unclear what vendors are being paid through this program and which have not been approved.

According to IPR, the governor’s office said the state is not a party to those transactions; it’s strictly between the vendor and qualified purchaser. But it said it is aware of who is participating.