Marginal rate against effective rate
California has nine income tax bands running from 1% to 12.3%, plus a 1% surcharge above $1,000,000. That headline range is why the state is called high-tax. The rate most people actually pay is much lower, and the gap between the two is the point of this calculator.
The formula
The deduction comes off first, the bands apply to what remains, and the exemption credit comes off the tax itself. The order matters: a credit of $153 is worth $153, while a deduction of $153 is worth only its band rate.
Worked example: $80,000, single filer, tax year 2025
- Standard deduction: $5,706, leaving $74,294 taxable
- Tax across the bands, before credit: $3,347.98
- Personal exemption credit: −$153
- State income tax: $3,194.98
- Marginal rate: 9.3% — effective rate: 4.0%
The marginal figure describes the next dollar; the effective figure describes the year. A raise is taxed at 9.3%. The salary as a whole is taxed at 4%.
Band by band
| Taxable income | Rate | Tax on this slice |
|---|---|---|
| $0 – $11,079 | 1% | $110.79 |
| $11,079 – $26,264 | 2% | $303.70 |
| $26,264 – $41,452 | 4% | $607.52 |
| $41,452 – $57,542 | 6% | $965.40 |
| $57,542 – $72,724 | 8% | $1,214.56 |
| $72,724 – $74,294 | 9.3% | $146.01 |
| Total before credit | $3,347.98 |
Only $1,570 of the $74,294 is taxed at 9.3%. Everything below it was taxed at 1% to 8% on the way up, which is why the effective rate lands where it does.
Filing status changes the bands, not the rates
Married couples filing jointly get bands twice as wide and a deduction of $11,412. On the same $80,000 the tax falls to $1,165 — an effective rate of 1.5% — because most of the income never leaves the 1% to 4% bands. Head of household sits between the two.
This is the single largest lever in the calculation, and it is why a couple and an individual on identical incomes can owe very different amounts.
What sits on top of the state tax
Federal income tax is a separate, larger bill. At $80,000 single it is roughly $9,200. Social Security and Medicare take another 7.65%. California also charges State Disability Insurance at 1.2% on all wages, with no ceiling since 2024.
Taken together, the state income tax is usually the third-largest deduction on a California pay stub, behind federal tax and payroll tax.
The mental health surcharge
Above $1,000,000 of taxable income an additional 1% applies, funding mental health services. It is why the top marginal rate is quoted as 13.3% rather than 12.3%, and it applies to the amount over the threshold, not to the whole income.
What this calculator leaves out
Federal tax, FICA and SDI, itemised deductions, dependent credits ($475 each), the renter's credit, and alternative minimum tax. Adjusted gross income is assumed equal to gross income, which understates the tax for anyone with untaxed benefits and overstates it for anyone with pre-tax retirement contributions.
Figures are the Franchise Tax Board's 2025 schedules, which apply to returns filed in 2026. The FTB indexes bands to inflation each autumn.
Related calculators
- California sales tax calculator — the other California levy
- FICA calculator — Social Security and Medicare on the same salary
- Federal tax bracket calculator — the larger bill on top