Well, the Interactive Brokers business entity of Timber Hill, LLC is NOT listed as a CME member firm - Timber Hill is. Looking at the CME membership directory, Interactive Brokers isn't Class A anything.
And since Timber Hill certainly prop trades and messages extensively for their own gain, my guess is that they will be pricks about this and stick our poor unfortunate OP with the tab. He can and should certainly protest it to both IB management and the CME if, in fact, he was never warned about the message issue beforehand. I have no idea what the IB client futures clearing contract agreement looks like, and if there is any verbage regarding the issue buried in there.
IB does have some discretion on how they pass on these surcharges according to CME member regulations:
"Do Class A firms pass on surcharge fees to their customers?
It is up to each Class A firm to decide how surcharge fees are distributed. However, CME Group-provided reports will be segregated by sub-firm, FIX tag 50, iLink session ID and account number so that the Class A firm can easily identify the origin
of trading activity."
Since Timber Hill is a designated market making firm by the CME, I am sure that all of their messaging quotas are used by their internal proprietary trading operations, and not by IB retail clearing clientele.
"CHICAGO, Sept. 30 /PRNewswire-FirstCall/ -- Chicago Mercantile Exchange Inc. (CME), the largest futures exchange in the U.S., today announced the selection of six leading trading firms to help fuel further growth its electronic E-mini⢠S&P 500® equity options market. The firms chosen to become market makers are: Citadel Derivatives Trading LLC, Chicago Trading Company, Deutsche Bank Securities, Inc., Goldman Sachs, Timber Hill and Wolverine Trading LLC."
"These newly selected firms join HGI Holdings, who began making markets in CME's E-mini S&P 500 equity options in November 2003. As market makers, they will provide continuous, transparent and competitive markets for CME E-mini S&P 500 equity options traded on GLOBEX. In return for their assistance in creating additional liquidity for all E-mini S&P 500 equity options customers, CME will provide its market makers with additional bandwidth."