About $23 million in tax money for the Chicago area's cash-starved transportation system will not be released early until the system promises to spread the money throughout six-county area it serves Gov. James R. Thompson said.

A previous accelerated sales-tax payment reportedly was used by the Regional Transportation Authority to keep only the Chicago Transit Authority in operation while some suburban carriers moved toward shutdowns.

The $23 million is in the form of a regular sales tax payment for the RTA originally due June 15, but officials were working on making the money available sooner than that.

Meanwhile, the RTA filed suit in Cook County Circuit Court to bar the Illinois Commerce Commission from interfering with RTA-subsidized suburban bus carrier.

The suit charges the ICC with trying to intimidate suburban bus companies by urging them to seek more money form the RTA or face revocation of their licenses.

Early yesterday, the Illinois Supreme Court reversed a lower-court ruling that ordered the RTA to take whatever steps were necessary to keep the transit system running. Judge Arthur Dunne said he had so ruled because the authority has a statutory duty to provide transit to the RTA area.