Educational use only. This guide is for
general educational purposes and is not financial, tax, legal, or accounting advice. Tax
rules can change and individual facts matter. Verify the information with official
sources and a qualified professional before making tax or financial decisions.
1. Annualize Pay and Deductions
Annual amount = paycheck amount × frequency multiplier
Annual frequency = 1, monthly = 12, biweekly = 26
Total gross = annual salary + annual bonus + annual stock rewards
Annual frequency = 1, monthly = 12, biweekly = 26
Total gross = annual salary + annual bonus + annual stock rewards
2. Federal Regular and Supplemental Withholding
Federal regular wages = annual salary - medical - 401(k) - HSA -
FSA
Regular withholding = bracket base + max(0, wages - prior bracket max) × bracket rate - eligible children × $2,000
Supplemental withholding = min(supplemental wages, $1,000,000) × 22% + max(0, supplemental wages - $1,000,000) × 37%
Regular withholding = bracket base + max(0, wages - prior bracket max) × bracket rate - eligible children × $2,000
Supplemental withholding = min(supplemental wages, $1,000,000) × 22% + max(0, supplemental wages - $1,000,000) × 37%
| 2025 federal withholding | Single | Married filing jointly |
|---|---|---|
| No-withholding band ends | $8,600 | $16,600 |
| 10% band ends | $20,550 | $40,500 |
| 37% bracket starts above | $635,000 | $793,550 |
3. Social Security and Medicare Withholding
FICA wages = total gross - medical - HSA - FSA
Social Security withholding = min(FICA wages, $176,100) × 6.2%
Medicare withholding = FICA wages × 1.45% + max(0, FICA wages - $200,000) × 0.9%
Social Security withholding = min(FICA wages, $176,100) × 6.2%
Medicare withholding = FICA wages × 1.45% + max(0, FICA wages - $200,000) × 0.9%
4. California Withholding and SDI
California taxable wages = total gross - medical - 401(k) - FSA
California withholding taxable income = max(0, California taxable wages - withholding standard deduction)
California withholding = California bracket tax - personal allowance credits
California SDI = FICA wages × 1.2%
California withholding taxable income = max(0, California taxable wages - withholding standard deduction)
California withholding = California bracket tax - personal allowance credits
California SDI = FICA wages × 1.2%
| 2025 California withholding item | Value |
|---|---|
| Withholding standard deduction: single / MFS | $5,540 |
| Withholding standard deduction: MFJ / head of household | $11,080 |
| Personal allowance credit | $163.90 |
| California SDI rate | 1.2% |