How the California Income Tax Calculator Works
Data Sources
| Source | Data Used | Official URL |
|---|---|---|
| IRS | Federal tax brackets, standard deductions, FICA rates | irs.gov |
| CA FTB | CA state brackets, standard deduction, CA SDI rate | ftb.ca.gov |
| SSA | Social Security wage base ($184,500 for 2026) | ssa.gov |
| CA EDD | SDI rate (1.3% with no wage cap, 2026) | edd.ca.gov |
| U.S. Treasury | Federal tax law changes (OBBBA, TCJA) | treasury.gov |
Calculation Method
In plain language, here's how the calculator gets from your gross income to your take-home pay:
- Your income is taxed in progressive brackets — each tier of income is taxed only at that tier's rate, not your whole income at your top rate.
- The standard deduction is subtracted before we compute your taxable income (unless itemizing produces a larger deduction, federally).
- FICA: Social Security is 6.2% up to the $184,500 wage base; Medicare is a flat 1.45% with no cap.
- CA SDI is 1.3% on all wages, with no wage cap — unlike Social Security, there is no ceiling on the wages it applies to.
- Net take-home = gross income − federal income tax − CA income tax − FICA − SDI.
Key 2026 Values Used
| Item | 2026 Value | Source |
|---|---|---|
| Federal standard deduction (single) | $16,100 | IRS |
| Federal standard deduction (MFJ) | $32,200 | IRS |
| SS wage base | $184,500 | SSA |
| CA standard deduction (single) | $5,706 | CA FTB |
| CA standard deduction (MFJ) | $11,412 | CA FTB |
| CA SDI rate | 1.3% (no cap) | CA EDD |
| Medicare rate | 1.45% | IRS |
| Additional Medicare (income > $200k) | 0.9% | IRS |
Known Limitations
This calculator does not account for:
- California does not conform to federal HSA deductions (CA taxes HSA earnings)
- California taxes capital gains as ordinary income (no preferential rate)
- AMT (Alternative Minimum Tax) — not calculated
- Self-employment tax — partially handled; complex SE situations need a CPA
- Pre-tax deduction employer matching specifics
- Spouse income interactions beyond MFJ selection
- Local city/county taxes (CA has none for income, but noted for clarity)
Update Schedule
We update all rates and brackets annually each January.
Last verified: January 2026 against IRS Rev. Proc. 2025-28 and CA FTB Publication 1005.
Methodology reviewed by Robert C. Johnson, CPA.