{"model":"mega-backdoor-roth","specVersion":"1.0.0","specUrl":"/api/v1/models/mega-backdoor-roth/spec","inputs":{"salary":{"kind":"float","min":50000,"max":500000},"traditional401kContribution":{"kind":"float","min":0,"max":23000},"employerMatch":{"kind":"float","min":0,"max":20000},"afterTaxContribution":{"kind":"float","min":0,"max":46000},"incomeTaxRate":{"kind":"float","min":0.1,"max":0.37},"annualReturn":{"kind":"float","min":0.02,"max":0.12},"yearsToRetirement":{"kind":"int","min":5,"max":40}},"arrayInputs":{},"constraints":["salary is a dead input by spec (accepted, no effect on outputs)"],"sentinels":[],"facts":[{"id":"irs.415c.overall-limit.2026","label":"IRC §415(c) overall defined-contribution limit","value":72000,"period":"TY2026","source":"IRS Notice 2025-67 / COLA increases table"}],"disclaimer":"Illustrative planning model, not financial advice. Outputs follow the published model spec exactly; read the spec for assumptions and exclusions before relying on any number."}