How a bonus is withheld in Texas
Texas has no state income tax and no local income taxes, so a bonus loses only the federal lines: income tax withholding at the flat 22% supplemental rate (or under the aggregate method), Social Security at 6.2% up to the $184,500 wage base, and Medicare at 1.45%. On a $10,000 bonus the percentage method withholds $2,200, $620 and $145, leaving $7,035. "How are bonuses taxed in Texas" is one of the most searched versions of the question, and the answer is: federally, exactly as everywhere else, and by the state not at all.
Under the aggregate method the bonus is added to a regular paycheck and federal withholding is computed on the combined amount under the normal tables. For a $60,000 earner paid every two weeks that withholds about $2,700 rather than $2,200 on a $10,000 bonus, because a $12,308 fortnight annualises to $320,000 and is withheld at that salary's rates. The extra is returned at filing.
What the withholding means for your federal return
A single filer on $60,000 has a federal marginal rate of 12% up to $50,400 of taxable income and 22% above it, so a $10,000 bonus is really taxed at about $1,450 against $2,200 withheld, and about $750 returns as part of the refund. A filer already in the 24% bracket, above $105,700 of taxable income, is under-withheld at 22% by about $200 per $10,000 and owes it in April. A Texas resident who earns a bonus for work in New Mexico, Oklahoma, Arkansas or Louisiana is withheld for that state. The Texas paycheck calculator shows the federal marginal rate for any salary.