Authoritative Data Source and Methodology
AuthoritativeDataSource: California Franchise Tax Board (FTB) — Personal Income Tax Rates and Schedules (official). Direct reference: https://www.ftb.ca.gov/file/personal/tax-calculator-tables-rates.asp . Accessed on 2025-09-13.
Tutti i calcoli si basano rigorosamente sulle formule e sui dati forniti da questa fonte.
The Formula Explained
$$\text{Taxable Income (TI)}=\max\{0,\,\text{Gross Income (GI)}-D\}$$
$$T_{\text{brackets}}=\sum_{i=1}^{n} r_i \cdot \max\bigl(0,\,\min(TI,\,u_i)-u_{i-1}\bigr),\quad u_0=0$$
$$T_{\text{MHS}}=0.01 \cdot \max\{0,\,TI-H_s\}$$
$$T_{\text{total}}=\max\{0,\,T_{\text{brackets}}+T_{\text{MHS}}-C\}$$
$$\text{Effective Rate}=\dfrac{T_{\text{total}}}{GI}, \quad
\text{Marginal Rate}=r_k + \mathbf{1}[TI>H_s]\cdot 0.01$$
where:
- D is the California deduction (standard or itemized),
- C is total nonrefundable CA credits,
- u_i are bracket upper bounds and r_i their rates,
- H_s is the Mental Health Services threshold for the selected filing status,
- r_k is the rate of the bracket containing TI.
Glossary of Inputs and Outputs
- Tax year: Loads the correct California rate schedule and standard deduction.
- Filing status: Single, Married Filing Jointly, Married Filing Separately, Head of Household.
- Gross income (GI): Annual income before California deductions.
- Deduction (D): Standard deduction for the year/status or your itemized deduction amount.
- Nonrefundable credits (C): Personal/dependent or other credits that reduce tax (not below zero).
- Taxable income (TI): Income subject to California tax after deductions.
- Tax before credits: Tax from progressive brackets plus surcharge, before subtracting credits.
- Mental Health Services Tax (T_MHS): 1% of TI above the threshold.
- Total California income tax (T_total): Final state tax after credits.
- Effective tax rate: T_total divided by GI.
- Marginal tax rate: Rate on your next dollar of taxable income (adds 1% if TI exceeds MHS threshold).
- After-tax income: GI − T_total.
How It Works: A Step-by-Step Example
Scenario: Tax year 2024, Single filer, Gross income = $120,000, Standard deduction, No credits.
- Compute deduction D (standard for 2024 Single): D = $5,363.
- Taxable income TI = 120,000 − 5,363 = 114,637.
- Apply progressive brackets up to TI; since TI is below the MHS threshold, T_MHS = 0.
- Sum bracket taxes to get tax before credits (approximately $7,286).
- No credits, so total California income tax ≈ $7,286.
- Effective tax rate ≈ $7,286 / $120,000 ≈ 6.07%.
- Marginal rate: 9.3% (the bracket containing TI).
Frequently Asked Questions (FAQ)
Does the calculator include California’s Mental Health Services Tax?
Yes. A 1% surcharge is added to taxable income over the applicable threshold (default $1,000,000 per return; $500,000 if Married Filing Separately).
Which deduction is used by default?
The California standard deduction for the selected tax year and filing status. You can switch to itemized and provide a custom amount.
Are personal and dependent exemption credits accounted for?
Enter their combined total in the Credits input. The calculator subtracts these (not below $0).
Is this estimate the same as my paycheck withholding?
Not necessarily. Withholding uses federal/state worksheets and allowances. This tool estimates annual liability based on your inputs.
Does the tool include federal taxes or local payroll taxes like SDI?
No. It estimates California personal income tax only. It does not compute federal tax or other payroll items.
Do capital gains get special rates in California?
No. California generally taxes capital gains as ordinary income at the same rates as wages.