401(k)/IRA Contribution & Match Optimizer 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

t5-208

Effect

Computation or source lookup only

Input and validation requirements

The raw annuity-with-growth formula produces a division-by-zero result when expected return equals annual raise unless the equal-rate limit is implemented. The salary-period convention can also change the result by a factor of twelve if monthly salary is mistaken for annual salary.

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": {
    "salary": 60000,
    "contribution_percent": 0.06,
    "match_cap_percent": 0.06,
    "match_rate": 0.5,
    "annual_raise": 0.03,
    "expected_return": 0.07,
    "years_to_retirement": 30,
    "contribution_timing": "end_of_year",
    "percent_units": "decimal"
  },
  "expected_outputs": {
    "projected_employee_balance": 466649.33,
    "annual_match_value": 1800,
    "annual_dollars_left_on_table": 0
  },
  "working": "Annual contribution = 60000 * 0.06 = 3600. FV factor = ((1.07^30 - 1.03^30) / (0.07 - 0.03)) = (7.61225504 - 2.42726247) / 0.04 = 129.62481425. Projected balance = 3600 * 129.62481425 = 466649.33. Match value = min(0.06, 0.06) * 60000 * 0.5 = 0.06 * 60000 * 0.5 = 1800. Full-match amount = 0.06 * 60000 * 0.5 = 1800. Dollars left = 1800 - 1800 = 0."
}

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-tranche5/tranche5-results.json