California Bonus Tax Calculator 2026

Estimate how much of a California bonus may reach your bank account after federal withholding, California PIT, Social Security, Medicare, Additional Medicare withholding when applicable, and California SDI. The calculator also compares the two main withholding approaches side by side, because the method used on a bonus can materially change the amount withheld from that check.

The result is a payroll-withholding estimate, not your final income-tax bill. A bonus is still wage income; the federal and California “bonus rates” you see on a pay stub are withholding rules used before your annual tax return reconciles what was withheld with what you actually owe.

2026 quick reference: where the optional federal flat method is permitted, federal supplemental withholding is 22% up to the $1 million cumulative supplemental-wage threshold; California’s flat PIT option is 10.23% for bonuses and stock options. A California bonus may also be subject to 6.2% Social Security, 1.45% Medicare, and 1.3% SDI, subject to the applicable wage rules.

How much is withheld from a California bonus in 2026?

For a separately timed cash bonus that qualifies for the flat percentage methods, a common 2026 withholding pattern is:

Component	2026 rule	What changes it
Federal income-tax withholding	22% optional flat rate	37% is mandatory on the portion of cumulative supplemental wages above $1 million.
California PIT withholding	10.23% flat option for bonuses and stock options	If California requires or payroll uses the aggregate calculation, state withholding is based on the regular PIT schedules instead.
Social Security	6.2%	Only the portion still below the 2026 $184,500 Social Security wage base is subject.
Medicare	1.45%	No wage-base ceiling.
Additional Medicare	0.9% employer withholding after $200,000 of calendar-year wages	Depends on Medicare wages already paid by that employer; employer withholding uses $200,000 regardless of filing status.
California SDI	1.3%	For wages subject to California SDI; 2026 has no taxable wage ceiling.

These percentages should not be added mechanically for every employee. Social Security can stop during the year, Additional Medicare can begin, and the income-tax withholding method may be aggregate rather than flat. That is why the calculator asks for regular pay and optional year-to-date wage information.

Official references: IRS Publication 15 (2026); California EDD 2026 Employer’s Guide (DE 44); EDD 2026 rates and withholding

Example: $10,000 California bonus using the flat percentage methods

Assume a $10,000 cash bonus, the employee is still below the 2026 Social Security wage base and the $200,000 Additional Medicare employer-withholding threshold, the payment is subject to California SDI, and the federal and California flat percentage methods are available and used. The estimate is:

Item	Estimated withholding
Gross bonus	$10,000.00
Federal supplemental withholding (22%)	-$2,200.00
California PIT (10.23%)	-$1,023.00
Social Security (6.2%)	-$620.00
Medicare (1.45%)	-$145.00
California SDI (1.3%)	-$130.00
Total withheld	-$4,118.00
Estimated net bonus	$5,882.00

In this example, 41.18% of the gross bonus is withheld before deposit. That does not mean the employee’s final income-tax rate on the bonus is 41.18%. Some of the amount is payroll tax, and federal/California income-tax withholding is reconciled with the employee’s full-year tax return.

Percentage method vs. aggregate method

The biggest reason two California bonus calculators can produce different answers is that supplemental wages can be withheld using different methods. Our tool shows both estimates so you can see the difference instead of assuming one method applies to every payroll situation.

Federal percentage method

Under IRS Publication 15, when a bonus or other supplemental wage is identified separately and federal income tax was withheld from the employee’s regular wages in the current or immediately preceding calendar year, an employer can generally use the optional flat 22% federal withholding method on supplemental wages up to the $1 million threshold. No other flat federal percentage can be substituted. The portion of calendar-year supplemental wages above $1 million is subject to mandatory 37% withholding.

Federal aggregate/difference method

The employer can instead combine the supplemental wage with the relevant regular wages, calculate withholding on the combined amount, subtract the income tax already withheld or to be withheld on the regular wages, and assign the difference to the supplemental payment. If federal income tax was not withheld from the employee’s regular wages in the current or immediately preceding year, IRS rules generally require the aggregate approach rather than the optional 22% method.

California percentage vs. aggregate treatment

California adds an important timing rule. The 2026 EDD Employer’s Guide says that when supplemental wages are paid at the same time as regular wages, the employer is required to treat the total as regular wages and calculate PIT using the regular withholding schedules. When the supplemental wage is not paid at the same time as the regular wages, California permits either an aggregate/difference calculation or a flat withholding option.

For that flat option, California uses 10.23% for bonuses and stock options that are wages subject to PIT withholding. Other supplemental wages, such as commissions, overtime pay, sales awards, severance and vacation pay, use a 6.6% flat option.

You normally do not choose the payroll method yourself. The calculator compares the methods for planning and explanation; it does not tell an employer which method is legally required or permitted for a specific payroll event.

Why can the two methods produce very different net bonuses?

The flat method applies fixed supplemental-withholding percentages. The aggregate method instead runs the combined wages through the employee’s regular federal W-4 and California DE 4 withholding calculations. That can make the estimated withholding higher or lower depending on regular pay, pay frequency, filing status, W-4 entries, DE 4 allowances and the size of the bonus.

For example, with a $1,000 bonus, a $2,000 monthly regular paycheck, single federal and California withholding status, and no additional W-4/DE 4 adjustments, the current calculator produces the following illustrative comparison:

Method	Estimated federal	Estimated CA PIT	Payroll taxes + SDI	Estimated net bonus
Percentage / separate-payment estimate	$220.00	$102.30	$89.50	$588.20
Aggregate / difference estimate	$112.50	$29.39	$89.50	$768.61

This example is designed to show how the withholding method can change the current check; it is not a prediction of which method a particular employer will use or of the employee’s final annual tax liability.

How to use the California bonus tax calculator

• 1. Enter the bonus or supplemental payment amount. Use the gross amount before taxes and deductions.
• 2. Choose the California supplemental-payment type. Select “Bonus or stock option” for the 10.23% California flat-option scenario; use “Other supplemental wage” only when the payment is another type covered by California’s 6.6% flat option.
• 3. Enter your regular gross paycheck and pay frequency. These are required for the aggregate/difference estimate.
• 4. Match your federal W-4 and California DE 4 settings. The aggregate result depends on the same withholding inputs used for a regular paycheck.
• 5. Add year-to-date supplemental, Social Security and Medicare wages when they matter. These three figures control different thresholds and should not be treated as one generic YTD number.
• 6. Compare the two estimated net bonuses and open the threshold trace to see which rates and limits were applied.

Why the calculator asks for three different YTD wage amounts

A single “wages earned this year” field is not enough for every bonus edge case. Three separate annual thresholds can matter:
• YTD supplemental wages: used to determine how much room remains below the $1 million federal supplemental-wage threshold before mandatory 37% withholding applies to the excess.
• YTD Social Security wages: used to determine how much of the current bonus is still below the 2026 Social Security wage base of $184,500.
• YTD Medicare wages: used to determine whether this employer has crossed the $200,000 threshold for Additional Medicare withholding.

This matters most for large bonuses and high earners. A generic calculator that applies 6.2% Social Security to the entire bonus can overstate withholding after the Social Security wage base has already been reached. Conversely, a calculator that ignores Additional Medicare can understate withholding once the employer’s $200,000 threshold is crossed.

What happens if your supplemental wages exceed $1 million?

The federal rule changes once cumulative supplemental wages paid to the employee during the calendar year exceed $1 million. The portion above that threshold is subject to federal income-tax withholding at 37%, without regard to the employee’s Form W-4. The calculator asks for YTD supplemental wages so it can split the current payment between the 22% portion and any mandatory 37% portion when necessary.

The $1 million rule applies to supplemental wages, not simply total salary. IRS Publication 15 also instructs employers to include supplemental wages from businesses under common control when applying the rule.

Are bonuses taxed differently from regular salary?

A bonus can be withheld differently from regular pay, but the flat withholding percentage is not a separate final federal or California income-tax rate. The IRS treats employer bonuses as wage income, and cash bonuses generally appear on Form W-2. Your annual return combines the relevant wage income and reconciles total tax liability against the income tax that was withheld during the year.

That is why “my bonus had 41% withheld” and “my final tax rate on this bonus is 41%” are not the same statement. Depending on your full-year income, filing status, deductions, credits and other withholding, the current bonus may contribute to a refund, reduce a refund, reduce an amount due, or leave additional tax due. A bonus calculator cannot determine that annual result from one paycheck alone.

See IRS Publication 525 – Taxable and Nontaxable Income for the treatment of employer bonuses as income, and IRS Publication 15 for supplemental-wage withholding rules.

Does California use 10.23% for every type of supplemental pay?

No. California’s 10.23% flat option is specifically listed for bonuses and stock options. The EDD lists a 6.6% flat option for other supplemental wages such as overtime, commissions, sales awards, severance and vacation pay. The flat options are also subject to California’s payment-timing rules; a supplemental payment made at the same time as regular wages is treated under the regular PIT schedules.

The calculator includes both California supplemental types because a user may receive several kinds of non-regular pay, but this page remains focused on bonuses. If you are trying to calculate legally owed overtime earnings before tax, use the dedicated California Overtime Calculator first.

Why might your real bonus check differ from the calculator?

• Your employer used a different permitted withholding method. The percentage and aggregate methods can produce very different current-check withholding.
• Your W-4 or DE 4 settings differ from what you entered. The aggregate calculation depends directly on filing status, W-4 adjustments, California allowances and additional withholding.
• You crossed a YTD wage threshold. Social Security can stop on part of a bonus after the annual wage base, while Additional Medicare can begin after the employer-paid wage threshold.
• The payment has a different payroll classification. A bonus/stock option uses a different California flat option from commissions, overtime, severance and other supplemental wages.
• Your wages are not subject to one of the standard payroll taxes. Certain employment or benefit-plan situations can change FICA or California SDI treatment.
• Payroll uses rounding or employer-specific system rules. Small differences can arise from rounding, timing and payroll configuration even when the underlying tax rules are the same.

California Bonus Tax Calculator FAQs

What is the California bonus withholding rate in 2026?

For the California flat supplemental-wage option, bonuses and stock options use 10.23% PIT withholding. Other supplemental wages such as commissions, overtime, sales awards, severance and vacation pay use 6.6%. When supplemental wages are paid at the same time as regular wages, California requires withholding on the combined payment under the regular PIT schedules.

Is the federal bonus tax rate 22%?

Twenty-two percent is an optional federal supplemental-wage withholding rate where IRS conditions for the flat method are met; it is not a special final tax rate on bonus income. The portion of cumulative supplemental wages above $1 million is subject to mandatory 37% federal withholding.

Why did I only receive about 59% of my California bonus?

If the federal 22% method and California 10.23% flat option apply, and the full payment is also subject to 6.2% Social Security, 1.45% Medicare and 1.3% SDI, the combined withholding is 41.18%. A $10,000 bonus under those assumptions would have an estimated $5,882 net payment.

Will I get the extra bonus withholding back as a refund?

Not necessarily. Income-tax withholding is credited against your annual tax liability. If total payments exceed your final liability, that can contribute to a refund; if withholding is insufficient, you may still owe. The outcome depends on the full tax return, not this bonus alone.

Does Social Security always come out of the entire bonus?

No. Employee Social Security is 6.2% only up to the 2026 wage base of $184,500. If year-to-date Social Security wages are already near the cap, only the remaining portion up to the cap is subject to the 6.2% employee tax.

Can I choose whether payroll uses the percentage or aggregate method?

Usually the employer/payroll process determines the legally permitted or required method. The calculator compares both so you can understand possible withholding outcomes; it is not an instruction to payroll.

Does this calculator estimate my tax refund?

No. It estimates payroll withholding and net bonus. A refund or amount due requires a full-year federal and California tax calculation, which is outside this page’s scope.

Calculate your regular paycheck or related California pay

• For normal salary, hourly wages, or a regular gross paycheck, use the California Paycheck Calculator.
• If you need to determine California regular, time-and-a-half, and double-time hours before estimating take-home pay, use the California Overtime Calculator.
• For a deeper explanation of federal withholding, California PIT, Social Security, Medicare, SDI and deductions on a normal paycheck, read How Much Tax Is Taken Out of a Paycheck in California?
• For formulas, source tables, assumptions and the annual update process, see How Our California Paycheck Calculator Works.