California vs Federal Taxes

A side-by-side comparison of California and federal income tax for 2026 — brackets, conformity, special deductions, and the quirks that catch people off guard.

The two systems, at a glance

Where California conforms with federal rules

California conforms — meaning it follows federal treatment — for many common items:

• Pre-tax 401(k), 403(b), 457(b) contributions reduce California taxable wages.
• Section 125 cafeteria-plan benefits (pre-tax health, dental, dependent care).
• Standard deduction concept (though dollar amounts differ).
• Filing status definitions.
• Most Schedule C business expense rules.
• Charitable contribution deductions if you itemize.

Where California does NOT conform

California has chosen not to conform with several federal provisions, which can produce surprising tax differences:

• HSA contributions. Federally, HSA contributions are above-the-line deductible. California does not conform — you must add back HSA contributions when calculating California taxable income, and HSA earnings are also California-taxable.
• QBI deduction (Sec. 199A, 20%). Federal only. California taxes the full net self-employment income.
• Bonus depreciation, Section 179 (partially). California limits Section 179 deductions and does not conform with federal bonus depreciation, requiring separate depreciation schedules for California returns.
• Capital gains preferential rates. Federally, long-term capital gains are taxed at 0/15/20%. California taxes capital gains at full ordinary rates, up to 13.3%.
• Mortgage interest cap. California still allows mortgage interest on up to $1M of acquisition debt, while federal caps at $750k for post-TCJA mortgages.
• Roth IRA conversion treatment of pre-87 IRAs: niche, but California sometimes deviates.

RSU and stock-comp differences

RSUs are treated similarly federally and in California: ordinary income at vesting, capital gains on sale of held shares. California, however, includes RSU income in its ordinary tax brackets — meaning RSU income contributes directly to whether you cross the 9.3%, 10.3%, 11.3%, or 12.3% California bracket. For multi-state employees who vested RSUs while a California resident, California claims tax on the full vesting income even if you later relocate.

Filing status quirks

• California recognizes domestic partnerships filing jointly, while federal does not.
• Married filing separately works similarly in both, though California has special rules for community property.
• Surviving spouse status (qualifying widow(er)) exists at both levels with similar rules.

Capital gains: the biggest divergence

Federally, long-term capital gains receive preferential rates: 0%, 15%, or 20% depending on income. California treats all capital gains as ordinary income, taxed at brackets up to 13.3%. For a high earner selling appreciated stock, the combined effective rate on a long-term gain in California is 23.8% federal (20% + 3.8% NIIT) plus 13.3% California = 37.1% — one of the highest in the country.

Implications for paycheck planning

Three takeaways for a California W-2 earner:

1. Pre-tax 401(k) is doubly powerful in California. Each dollar saves your federal + California marginal rate combined — often 28–35%.
2. HSA contributions still save federal tax + FICA but not California tax. Still worth doing for most people, but the math is different than what generic personal-finance sites assume.
3. For self-employed Californians, the QBI deduction\'s federal-only nature means California freelancers see a smaller benefit from going solo than freelancers in states that conform.

Use the calculators to see the difference

Run a salary through the paycheck calculatorto see how California layers on top of federal. Or try the 1099 calculator to see exactly how much QBI saves you federally — and how California still taxes the full amount.