Quarterly Estimated Tax Planner implementation

Binding contract

This record describes what an executable surface must bind and validate. It does not claim that a public calculator, package, or production route is deployed.

Record owner

Guth Instruments

Lifecycle

verified-clean

Evidence ID

t7-081

Effect

Computation or source lookup only

Input and validation requirements

The specification does not define validation for negative tax inputs or distinguish tax liability from refunds and credits. If a negative prior-year amount is accepted literally, the formula produces a nonsensical negative quarterly payment. Extreme finite inputs do not overflow in this test, but they expose a significant floating-point precision hazard. Year-dated safe-harbor rates and due-date tables also require explicit selection and validation.

Required corrections

No binding erratum is attached to this unique-name record. Implementers must still preserve the declared units, domain, and failure behavior.

Inspectable interface fixture

The sample below is evidence for interface and validation tests, not a production implementation.

{
  "inputs": {
    "tax_year": 2025,
    "projected_current_year_tax_usd": 10000,
    "prior_year_tax_paid_usd": 9000,
    "high_income_taxpayer": false,
    "installment_method": "regular_equal_installments"
  },
  "expected_outputs": {
    "safe_harbor_annual_payment_usd": 9000,
    "per_quarter_payment_usd": 2250,
    "due_dates": [
      "2025-04-15",
      "2025-06-16",
      "2025-09-15",
      "2026-01-15"
    ]
  },
  "reference_data": {
    "current_year_safe_harbor_percentage": {
      "value": 0.9,
      "source_convention": "IRS Form 1040-ES, 2025; widely tabulated federal estimated-tax safe-harbor rule"
    },
    "prior_year_safe_harbor_multiplier": {
      "value": 1,
      "source_convention": "IRS Form 1040-ES and IRS Publication 505, 2025; widely tabulated standard-income prior-year rule"
    },
    "due_date_rows": [
      {
        "installment": 1,
        "due_date": "2025-04-15",
        "source_convention": "IRS Form 1040-ES, 2025 federal individual estimated-tax calendar"
      },
      {
        "installment": 2,
        "due_date": "2025-06-16",
        "source_convention": "IRS Form 1040-ES, 2025 federal individual estimated-tax calendar"
      },
      {
        "installment": 3,
        "due_date": "2025-09-15",
        "source_convention": "IRS Form 1040-ES, 2025 federal individual estimated-tax calendar"
      },
      {
        "installment": 4,
        "due_date": "2026-01-15",
        "source_convention": "IRS Form 1040-ES, 2025 federal individual estimated-tax calendar"
      }
    ]
  },
  "working": "Current-year safe harbor = 10,000.00 × 0.90 = 9,000.00. Prior-year safe harbor = 9,000.00 × 1.00 = 9,000.00. Selected annual target = min(9,000.00, 9,000.00) = 9,000.00. Quarterly payment = 9,000.00 ÷ 4 = 2,250.00. The four dates are direct lookups from the 2025 IRS calendar."
}

Other records

Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

• VERIFIED_LEDGER.json
• evidence-tranche7/tranche7-results.json