{
  "taxYear": 2026,
  "jurisdiction": "US federal",
  "lastVerified": "2026-07-29",
  "calculationBasis": "Estimated annual income-tax liability using published tax brackets and the standard deduction; this is not the IRS payroll-withholding worksheet.",
  "standardDeductions": {
    "single": 16100,
    "married": 32200,
    "married_separate": 16100,
    "head": 24150
  },
  "brackets": {
    "single": [[0, 0.10], [12400, 0.12], [50400, 0.22], [105700, 0.24], [201775, 0.32], [256225, 0.35], [640600, 0.37]],
    "married": [[0, 0.10], [24800, 0.12], [100800, 0.22], [211400, 0.24], [403550, 0.32], [512450, 0.35], [768700, 0.37]],
    "married_separate": [[0, 0.10], [12400, 0.12], [50400, 0.22], [105700, 0.24], [201775, 0.32], [256225, 0.35], [384350, 0.37]],
    "head": [[0, 0.10], [17700, 0.12], [67450, 0.22], [105700, 0.24], [201750, 0.32], [256200, 0.35], [640600, 0.37]]
  },
  "fica": {
    "socialSecurity": {
      "employeeRate": 0.062,
      "taxableWageBase": 184500
    },
    "medicare": {
      "employeeRate": 0.0145,
      "additionalRate": 0.009,
      "additionalThresholds": {
        "single": 200000,
        "married": 250000,
        "married_separate": 125000,
        "head": 200000
      },
      "employerWithholdingThreshold": 200000
    }
  },
  "sources": [
    {
      "label": "IRS Revenue Procedure 2025-32 / Internal Revenue Bulletin 2025-45",
      "url": "https://www.irs.gov/irb/2025-45_IRB",
      "supports": ["2026 brackets", "2026 standard deductions"]
    },
    {
      "label": "IRS Publication 15-T (2026)",
      "url": "https://www.irs.gov/publications/p15t",
      "supports": ["payroll-withholding methodology reference"]
    },
    {
      "label": "SSA contribution and benefit base",
      "url": "https://www.ssa.gov/OACT/cola/cbb.html",
      "supports": ["6.2% employee rate", "2026 wage base"]
    },
    {
      "label": "IRS Topic 560",
      "url": "https://www.irs.gov/taxtopics/tc560",
      "supports": ["Additional Medicare Tax rate and thresholds"]
    }
  ],
  "notes": [
    "Federal results estimate annual tax liability, not exact Form W-4 withholding.",
    "Credits, itemized deductions, dependents, multiple jobs, tips/overtime deductions, and other tax-return adjustments are not modeled.",
    "Additional Medicare Tax liability uses filing-status thresholds; employers generally begin withholding at $200,000 regardless of filing status."
  ]
}