California Bonus Calculator
Bonus Details
Federal W-4 Settings
California Withholding (Form DE-4)
Deductions (Per Regular Paycheck)
Year-To-Date Data (Optional, Improves Accuracy)
Your Bonus Estimate
- Bonuses are not taxed at a special bonus rate when you file. They are ordinary income taxed at your regular marginal rate.
- The 22 percent federal flat rate and the 10.23 percent California flat rate are simply withholding methods employers use on supplemental wages paid separately.
- California applies a flat 10.23 percent supplemental withholding rate to bonuses. Additionally, California State Disability Insurance (SDI) is withheld at 1.2 percent on all wages with no wage cap starting in 2024.
- If your bonus is combined with a regular paycheck (aggregate method), withholding is computed on the combined amount using your W-4 and DE-4. This can push that single check into a higher bracket, which is why bonuses often look over-taxed in the pay period.
- When you file your return, your total annual income determines your true liability. Over-withholding on the bonus becomes part of your refund. Under-withholding becomes tax due.
- Gross-up mode solves for the gross bonus your employer must pay so your take-home equals the target you enter.
What Is the California Bonus Calculator?
The California Bonus Calculator is a 2025 payroll withholding estimator for employee bonuses. It uses your bonus amount, annual salary, pay frequency, federal filing status, W-4 settings, California DE-4 allowances, deductions, withholding methods, and optional year-to-date payroll information. It can calculate take-home pay from a gross bonus or solve for the gross bonus needed to reach a chosen net amount.
The California bonus calculator subtracts estimated federal income tax withholding, California withholding, Social Security, Medicare, Additional Medicare Tax, and applicable California SDI from the gross bonus. The result is an estimated bonus take-home amount, along with an effective withholding rate, tax breakdown, full-pay-period estimate, and annual income-tax snapshot.
How the California Bonus Calculator Withholding Formula Works
The calculator starts with the gross bonus and subtracts every withholding amount assigned to that bonus.
- B is the gross bonus.
- F is federal income tax withheld from the bonus.
- CA is California income tax withheld from the bonus.
- SS is Social Security tax assigned to the bonus.
- M is Medicare tax on the bonus.
- AM is Additional Medicare Tax assigned to the bonus.
- SDI is California State Disability Insurance withholding when the VPDI option is not selected.
With the California flat method, the code withholds 10.23% of the gross bonus for California income tax.
California SDI is calculated at 1.2% of the bonus unless you select the VPDI checkbox. In that case, the calculator sets SDI withholding to zero.
The federal flat method normally applies 22% while cumulative supplemental wages remain within $1,000,000. Any bonus portion above the remaining threshold is withheld at 37%. Federal and California aggregate methods instead compare withholding on combined regular wages plus the bonus with withholding on regular wages alone.
For example, use a $5,000 bonus, $75,000 annual salary, biweekly pay, Married Filing Jointly status, zero deductions and allowances, no prior year-to-date wages, and the flat federal and California methods. Federal withholding is $1,100. California withholding is $511.50. Social Security is $310, Medicare is $72.50, Additional Medicare is $0, and SDI is $60.
The estimated bonus take-home is $2,946.00. Total withholding is $2,054.00, giving an effective withholding rate of 41.08%. Results can change near the Social Security wage base, the Additional Medicare threshold, or the $1,000,000 federal supplemental wage threshold.
How to Use the California Bonus Calculator: Step by Step
- Select Estimate take-home from a bonus amount to enter a gross bonus, or choose gross-up mode to enter a desired net bonus.
- Enter the bonus amount. The value must be greater than zero.
- Choose the federal withholding method: Flat 22 percent or Aggregate.
- Choose the California withholding method: Flat 10.23 percent or Aggregate.
- Enter your Base Annual Salary and select weekly, biweekly, semimonthly, or monthly pay frequency.
- Select Single, Married Filing Jointly, or Head of Household for federal filing status.
- Enter any applicable W-4 Step 3 credits, Step 4(a) income, Step 4(b) deductions, Step 4(c) extra withholding, and Step 2 selection.
- Enter your California DE-4 allowances and any extra California withholding per check. Select the VPDI option if you do not pay SDI.
- Add pre-tax and post-tax deductions that apply to your regular paycheck.
- Enter available year-to-date Social Security wages, Medicare wages, supplemental wages, pay periods, and federal or California withholding.
- Check the acknowledgment box, then calculate your result.
The main output is your estimated bonus take-home after all coded withholding. You also see the effective withholding rate and each tax component. The tool shows regular-plus-bonus pay-period totals, annual federal and California tax estimates, annual SDI, and a projected income-tax refund or amount due. Gross-up mode also displays the required gross bonus.
Factors That Can Affect Your California Bonus Calculator Result
Flat Versus Aggregate Withholding
The calculator lets you choose the federal and California methods separately. Under the federal flat method, the coded supplemental rate is generally 22% below the $1,000,000 cumulative threshold. California's flat bonus method uses 10.23%. The tool also calculates the result under the alternative method and displays that amount for comparison.
Under an aggregate method, the code adds the bonus to one period of regular taxable wages. It then annualizes the combined amount through the applicable withholding calculation. The bonus portion is the difference between combined-pay withholding and regular-pay withholding. Because of that method, the aggregate result can differ sharply from a flat-rate result.
California SDI and VPDI
The calculator applies a 1.2% SDI rate to regular wages and the bonus. The code does not apply an SDI wage cap. If you check the VPDI option, the SDI rate becomes zero throughout the calculation. This changes bonus take-home, regular-pay taxes, annual SDI, and the California taxable-wage calculation used by the tool.
| Item | Rule Used in the Calculator |
|---|---|
| Federal flat bonus withholding | 22%, with 37% above the applicable $1,000,000 supplemental wage threshold |
| California flat bonus withholding | 10.23% |
| Social Security | 6.2% up to the remaining 2025 wage base of $176,100 |
| Medicare | 1.45% |
| Additional Medicare | 0.9% above the coded $200,000 wage threshold |
| California SDI | 1.2% unless VPDI is selected |
| DE-4 allowance value | $163.90 reduction in annual California taxable wages per allowance |
Regular-Pay Deductions and California Taxable Wages
Pre-tax deductions reduce regular federal taxable wages in the code. California regular taxable wages are reduced by both the entered pre-tax deduction and calculated SDI. The calculator does not reduce Social Security or Medicare wages for the entered pre-tax deduction. Post-tax deductions reduce full-pay-period take-home without changing the calculated taxes.
Both deduction inputs are capped internally at the regular gross pay for one period. They are regular-paycheck deductions, not direct bonus deductions. California allowances are converted to whole numbers and reduce annual California taxable wages by $163.90 each in the regular withholding and annual tax calculations.
Year-to-Date Data and Annual Estimates
Prior Social Security wages determine how much of the $176,100 wage base remains. Prior Medicare wages affect Additional Medicare withholding. Prior supplemental wages determine whether the federal bonus crosses the $1,000,000 threshold. Pay periods already received and prior federal and California income tax withholding affect the calculator's projected refund or amount due.
The calculator also accepts year-to-date SDI already withheld. However, that value does not change any displayed result in the current code. Annual SDI is instead calculated from the salary, bonus, pay frequency, and VPDI setting. The projected filing result compares projected federal and California income-tax withholding with estimated federal and California income-tax liability, excluding SDI.
All results are estimates based on the calculator's coded 2025 rules. Actual payroll withholding and final tax liability may differ because of employer payroll procedures, other income, deductions, credits, tax-law changes, and personal circumstances not represented by the tool. The calculation should not be treated as tax, payroll, or legal advice.
Frequently Asked Questions
How much tax is withheld from a bonus in California?
The total depends on several separate withholding calculations. This calculator can include federal income tax, California income tax, Social Security, Medicare, Additional Medicare Tax, and California SDI. With the flat methods selected, the code uses 22% federal withholding and 10.23% California withholding before adding the applicable payroll taxes.
What is the California bonus tax rate?
This calculator uses 10.23% as California's flat supplemental withholding rate when the flat California method is selected. That is a withholding rate, not the total amount removed from the bonus. Federal withholding, Social Security, Medicare, Additional Medicare Tax, and SDI may also reduce the estimated bonus take-home.
Why does a California bonus have so much withheld?
A bonus can have several withholding amounts applied at the same time. Under this calculator's flat settings, federal withholding is 22% and California withholding is 10.23%. Social Security, Medicare, and 1.2% SDI can also apply. These combined amounts can make the percentage withheld from a bonus look much larger than one tax rate alone.
What is the difference between flat and aggregate bonus withholding in California?
The flat methods apply the coded supplemental rates directly to the bonus. The aggregate methods calculate withholding after adding the bonus to regular taxable pay, then subtract the regular-pay withholding amount. Federal and California methods can be selected independently, and the calculator displays the corresponding alternative-method withholding for each jurisdiction.
Does California SDI apply to my bonus in this calculator?
Yes, unless you select the VPDI option. The calculator applies SDI at 1.2% to both regular gross wages and the gross bonus, with no wage cap in its code. If you indicate that you have a Voluntary Plan for Disability Insurance, the calculator sets its SDI withholding rate to zero.
Do California DE-4 allowances reduce withholding on my bonus?
They affect the aggregate California calculation but not the flat 10.23% bonus calculation. The calculator values each DE-4 allowance at $163.90 and subtracts the allowance amount from annualized taxable wages when calculating regular California withholding, aggregate withholding, and the annual California income-tax estimate.
How do I gross up a bonus in California?
Select gross-up mode and enter the bonus take-home amount you want to receive. The calculator repeatedly tests gross bonus amounts until the estimated net bonus reaches the target. It uses a binary-search process and then rounds the required gross bonus upward to the next cent before calculating the final withholding breakdown.
How accurate is the California Bonus Calculator?
It is an estimate based on the specific 2025 federal and California rates, thresholds, deductions, and formulas coded into the calculator. Accuracy depends on the data you enter. Actual payroll results and your final tax return may differ because employers and tax returns can include factors that this calculator does not model.