How Kansas withholds on a bonus
Kansas's withholding guide (KW-100) lets employers withhold a flat 5% on supplemental wages paid separately from regular pay. That sits between the state's two rates, 5.2% below $23,000 of taxable income and 5.58% above, so it slightly under-withholds for most filers. On a $10,000 bonus the percentage method withholds $2,200 federal, $620 Social Security, $145 Medicare and $500 Kansas, leaving $6,535. Kansas has no local income taxes.
Under the aggregate method Kansas applies its brackets to the combined paycheck, which for a $60,000 earner withholds at 5.58% on most of the bonus, about $558 rather than $500; the federal line rises to about $2,700. Kansas's large $9,160 exemption and $3,605 deduction have normally been used up by salary, so a bonus is taxed at 5.2% or 5.58% on the return.
What the withholding means for your Kansas return
Kansas's 5% supplemental rate is a little below the 5.58% most bonuses are finally taxed at, so the state line on a bonus produces a small balance due, roughly $60 on $10,000, rather than a refund. The federal side runs the other way: a $60,000 single filer's marginal federal rate is 12% to 22% against 22% withheld, so roughly $750 returns. Missouri residents who earn a bonus in Kansas are withheld for Kansas and credit it at home. The Kansas paycheck calculator shows the marginal rates for any salary. Allowances on Kansas Form K-4 do not reduce the flat 5% withheld from a separately paid bonus; they apply only under the aggregate method.