While no state has gone as far as Kansas, four others — Missouri, Ohio, Oregon and South Carolina — have passed laws in the last decade that give some small-business owners lower tax rates than wage earners.

By creating this preference for some types of income over others, Kansas has run into at least five problems:

It’s sometimes possible to turn taxable salary income into untaxed “business” income.

The Times has me on its staff, but it could commission freelance work from me instead. Income from the same work would then become tax-free under the Kansas rules.

Jim Dunning Jr., managing partner of Dunning & Associates C.P.A.s in Wichita, says he has seen a few clients change the way their businesses are incorporated to take advantage of the tax law. Many small firms are structured as S-corporations, and federal law requires an S-corporation’s owner-managers to pay themselves at least a “reasonable” salary. But by converting to a limited liability company, or L.L.C., owners can set their salaries to zero and take all of their income from the company as profits, thus avoiding any Kansas tax.

A lot of the beneficiaries of the tax break won’t be small businesses.

Many are sole proprietors like me, who are fundamentally engaged in labor, not entrepreneurship, and aren’t likely to hire anybody just because they receive a tax break.

At the other end of the spectrum, there’s no size limit on “small businesses” as defined by Kansas and the Internal Revenue Service. The Kansas tax break does not extend to C-corporations, the typical corporate form used by large publicly traded companies. But large companies can be structured in forms typically used by small businesses. For example, as of 2005, only 0.2 percent of business partnerships — which Kansas counts as small businesses — had earnings of more than $50 million, but they accounted for 57 percent of all partnership earnings.