South Carolina Bonus Tax Calculator 2026
South Carolina has no flat bonus rate in its 2026 withholding publications, so the bonus is added to regular pay under the WH-1603F formula — 6% for most salaried employees.
Bonus check calculator
Run through the 2026 formula
South Carolina's withholding publications for 2026 — the WH-1603 tables and the WH-1603F Formula for Computing South Carolina 2026 Withholding Tax (Rev. 11/4/25) — contain no separate supplemental rate. This calculator adds the bonus to the regular paycheck and withholds the extra South Carolina tax the formula produces.
Allowances and the 10% deduction
WH-1603F annualizes wages, subtracts $5,000 for each allowance and, if at least one allowance is claimed, a standard deduction of 10% of gross wages capped at $7,500. Employees who claim zero allowances get neither deduction. Taxable income is withheld at 0% up to $3,640, 3% to $18,230 and 6% above. For the standard example (zero allowances) the bonus adds $300.00; with two allowances, $300.00 — the same marginal 6% once regular pay clears the deductions. A worker on $600 every two weeks with zero allowances sees $296.97.
Checking the formula against the table
The Department's own example — $750 a week, three allowances — annualizes to $39,000, subtracts $15,000 of allowances and a $3,900 standard deduction, and withholds $549.90 a year, or $10.58 a week. The calculator's formula reproduces it.
| Rule | No flat rate: WH-1603F formula, top bracket 6% |
|---|---|
| Valid through | December 31, 2026 |
| Documents | WH-1603F Formula for Computing South Carolina 2026 Withholding Tax (Rev. 11/4/25) |
| Agency | South Carolina Department of Revenue |
| Federal income tax | −$1,100.00 |
| Social Security | −$310.00 |
| Medicare | −$72.50 |
| South Carolina income tax | −$300.00 |
| Net | $3,217.50 |