Lawmakers in a House panel are gearing up for discussion of windfall tax reform and a bill that would lower the sales tax burden on food.

Complicating the issues are unstable revenue estimates that indicate corporations may end up paying a lot more in income taxes than estimated after changes in federal code.

Chris Courtwright, with Legislative Research, said Monday it is possible the tax savings for multinational corporations in Senate-approved legislation will be greater than anticipated. Senate Bill 22 was estimated to save corporations $137 million when it passed the Senate last week.

After revising corporate income projections upward by $69 million in November, those collections still have outpaced the estimate by $28 million, Courtwright said.

One possible explanation: Big businesses have more at stake through repatriation and offshore profits than previously realized.

"I'm not saying it's some of it, most of it, all of it, any of it necessarily," Courtwright said, "but certainly that's a possibility that we're going to have to investigate and get to the bottom of. I don't think there's been any dramatic increase in corporate profits beyond the slight amount we acknowledged in November, so something else is clearly going on."

Courtwright said the top 1 percent of filers are responsible for 65 to 70 percent of corporate income tax receipts.

Rep. Steven Johnson, a Republican from Assaria and chairman of the House Taxation Committee, said he expects to work the tax reform bill next week.

Johnson also introduced a bill that would lower the sales tax on food by 1 percent from the statewide rate of 6.5 percent.

He said he wanted to vet arguments on the food exemption in a committee setting, rather than proposed amendments to a tax plan before the full chamber.

"I anticipate we would get the amendment on the floor, so I thought this would be a good place to start that discussion and the various pieces that may be in play," Johnson said.

He said the 1 percent cut was only a starting point for discussion, and that it could be offset through a proposal for recovering taxes on online sales.

Overall, the state's revenue picture is $39 million below the forecast for this fiscal year, which ends June 30.

Johnson noted revenues are within 1 percent of the estimate, and Courtwright advised lawmakers to disregard any "cliffhanger punditry" they see on Twitter.

Other factors affecting recent revenue reports: The federal shutdown, an underperforming oil industry and the lack of growth in sales receipts since summer.

Courtwright also talked about public outcry over lower-than-expected federal tax reforms, which he attributed to employers not withholding enough following complicated revisions to corporate tables. The state could see sales tax collections fall behind projections in the coming months, he said, because people won't have anticipated money to spend from federal returns.