An executive of IntercontinentalExchange Inc. (ICE) told Illinois lawmakers Friday that it might wind up paying more in state taxes under a bill aimed at reducing the tax burden for rival CME Group Inc. (CME).

Martin Hunter, vice president of tax and treasurer at ICE, testified before the Illinois House of Representatives's Revenue and Finance Committee, which is considering a plan that would drastically reduce taxes for derivatives exchanges on trades performed on their electronic platforms.

Without tax relief, CME and options exchange CBOE Holdings Inc. (CBOE) has warned it might move the bulk of its operations from Illinois, which has been CME's home for 163 years.

State lawmakers are considering a measure that would tax exchanges on 27.54% of electronic transactions, which account for the vast majority of all business done at CME and CBOE. Currently, taxes are paid on all electronic trades.

The 27.54% figure came from U.S. census data to approximate how much of the Chicago exchanges transactions are performed in Illinois, state officials said.

At Friday's hearing, Hunter said Atlanta-based ICE earns a "significant allocation of our income" from Illinois, although he said he was "not comfortable" providing further information in a public forum. ICE employs almost 100 people in Illinois, according to Hunter.

The ICE executive says the exchange industry is "very diverse," and it would be difficult to come up with "one-size-fits-all" rules.

Hunter requested that exchanges have the option of being taxed by the current "market-based" method, which state lawmakers say is included in the Senate's version of the bill.

CME has no objection to the measure containing an opt-out clause, said the ICE official and committee members.

ICE and New York-headquartered NYSE Euronext (NYX), and Nasdaq OMX Group Inc. (NDAQ) joined forces to hire a lobbyist representing their interests as the bill works its way through the state legislature.

Lawmakers in January voted to raise the state's corporate income tax to 7%, from 4.8%, to plug mammoth budget holes. The increase cost CME an extra $50 million per year, according to CME Chairman Terry Duffy.

Duffy told the committee earlier this month that it's "not acceptable" for CME to pay 6% of the state's entire corporate income tax.

The legislation would cut CME and CBOE's taxes by about half, state officials said.

The bill has ballooned to encompass much broader tax policies in an effort to garner bipartisan report. It includes incentives to keep Sears Holdings Corp. (SHLD) in Illinois.

Other provisions grant a multi-year extension of research and development tax credits for all Illinois businesses. And the state's Democratic Governor Pat Quinn has pushed for earned income tax credits and personal exemptions to help Illinois workers.

Cost estimates for the total package top $800 million by fiscal year 2014.

Republican state Rep. Ed Sullivan, Jr. said he is skeptical whether workers' tax relief creates or retain jobs.

However, other parts of the package are expected to reduce the state's jobless rate by about a full percentage point, adding approximately $600 million in revenue each year, said Sullivan, who serves on the Revenue and Finance Committee.

"It comes down to what the Governor is willing to concede on, and what we're willing to pass," added Sullivan.

Legislative leaders will work "diligently" through the Thanksgiving holiday to draft a final proposal, said committee chairman Rep. John Bradley.

"We obviously don't know what's going to be in that proposal," said Bradley.

The committee scheduled a vote for Nov. 28. If approved it would move to the full House and Senate the following day.

-By Howard Packowitz, Dow Jones Newswires; 312-750-4132; howard.packowitz@dowjones.com

--Jacob Bunge contributed to this article.