The Securities and Exchange Commission filed suit yesterday alleging a complex rebate scheme involving 7 investment advisers, 5 banks and 12 broker dealers.

Named in a civil suit filed at U.S. District Court here were Investment Information Inc. (III) of Dallas and its chairman, Frederick P. Oman.

These defendants were at the center of the alleged scheme, according to the SEC. Both consented to the SEC action without admitting or denying the allegations.

The SEC also filed suit against two banks, American National Bank & Trust of New Jersey and Security First National Bank in Sheboygan, Wisc. These defendants are contesting the SEC action.

The SEC charged that III brought together money managers (investment advisers and bank trust departments) and broker dealers.

The money managers directed business to brokers designated by III. These brokers then allegedly rebated about 50 percent of their commissions earned on the business to III.

The SEC says some $11.7 million in commissions was generated by this arrangement between January 1973 and June 1978.

According to the complaint, III took out about 10 percent of the 50 percent rebate as its fee. The balance then was used to pay for goods and services acquired by the money managers.

The money managers allegedly would simply submit bills for anything from computers to magazine subscriptions to III. III would pay the bills out of the amounts rebated by the brokers.

Federal securities laws provide that "reasonable" commissions can be paid to brokers for "brokerage and research services."

The services "must be provided by a broker effecting the transaction," the SEC said in a report accompanying yesterday's action.