President Obama today proposed eliminating corporate tax loopholes and using the money to cut the business tax rate to 28 percent from 35 percent. The tax code “is unnecessarily complicated and forces America’s small businesses to spend countless hours and dollars filing their taxes,” he said in a statement.

Strange, then, that a plan to simplify the business tax code and cut rates would spark a condemnation from small business groups, according to Bloomberg Businessweek. This chart tells you why:

The lower rate would only apply to companies organized as C corps, which pay corporate income taxes. They make up less than 6 percent of business tax returns, according to IRS data. (They account for closer to two-thirds of all business revenue and income.) For the rest of the business world, including partnerships, sole proprietors, S corps, and limited liability companies, their business earnings flow through to owners’ personal income and are taxed at individual income tax rates.

Eliminating tax breaks without lowering individual income tax rates could effectively raise taxes on some small business owners, says Todd McCracken, president of the National Small Business Association, a Washington trade group. “The business deductions are relatively unified. A deduction’s a deduction, whether you’re a C corp or a sole proprietor, for the most part,” he says.

McCracken likes some parts of the Obama proposal: A plan to make permanent deductions for capital investment (such as equipment and software) and research and development. (Yes, the tax reform supposedly eliminating deductions includes plans to expand deductions.) Still, he says, reforming the corporate tax code and letting the Bush tax cuts expire could leave non-corporate business owners facing a federal income tax rate of over 40 percent next year on earnings over $250,000.

The National Federation of Independent Business, a frequent foe of the Obama White House, panned the proposal, saying in a statement that “the focus should be on individual rate reform.” Not every small biz lobby agrees. Small Business Majority, a group that generally supports Obama’s policies, praised the plan and noted that “reforming the tax code will eliminate dozens of loopholes that consistently leave small businesses paying an unfair share of taxes.”

McCracken says the plan is short on specifics but looks like a mixed bag. He favors reform that would tackle the individual tax code alongside corporate taxes. The chances of any major tax plan passing in Congress this year, he notes, are very slim. So even if corporate tax reform spells trouble for small businesses, they probably don’t have to worry about it any time soon.