Deterministic formulas, zero generative hallucination
Every calculation on CostAnswer runs on a compiled, unit-tested mathematical engine in lib/calculations/. Generative AI is strictly prohibited from evaluating numbers, guessing tax brackets, or approximating payments. When you ask for a mortgage payment, an income tax estimate, or inflation adjustment, the math is computed using statutory rules from the Internal Revenue Code, Title 38, or standard amortizing annuities.
Cryptographic provenance and automated freshness gates
We do not fetch raw web pages on the fly as you type. Instead, we ingest primary datasets directly from federal and state agencies (IRS, BLS, EIA, Freddie Mac, HUD, Census, BEA, USDA, NAIC, CMS, FHFA). Each snapshot is sealed with a SHA-256 cryptographic hash and checked against its provider’s publication calendar. If a release is delayed or fails validation, the last verified copy stays up—the math never breaks or hallucinates.
Data boundaries: what we include vs. what we exclude
Trust requires knowing what a tool does not do. CostAnswer provides comprehensive federal and 50-state/D.C. baselines, but intentionally excludes proprietary algorithmic black-boxes (such as private auto insurer telematics or secret credit-tier surcharges) and municipal-level local income taxes that require street-level geocoding. Where a local or proprietary variable exists, our calculators provide neutral regional averages and allow you to enter your exact quote or rate.
Tracking four decades of economic shifts (1980 – 2026)
Economic numbers make the most sense in context. On our data sources page, we publish an official multi-decade historical progression tracking CPI-U inflation, purchasing power of \$100, 30-year fixed mortgage rates, standard deductions, 401(k) limits, and loan ceilings from 1980 to today.
Separation of math, benchmarks, and planning extras
A slab’s cubic yardage is an exact physical measurement; the number of extra bags to order for spillage is a planning allowance. Cost and materials tools always separate measured statutory figures from planning buffers.
If an official figure changes
When the BLS publishes new CPI numbers, Freddie Mac updates weekly PMMS surveys, or the IRS releases annual inflation adjustments, snapshot version identifiers and publication receipts update transparently. Older calculations remain pinned to their historical snapshots.
Common questions about what an estimate is, and what it is not, are answered in detail on the FAQ.
Explore the live data registry, data scope matrix, and 1980–2026 historical progression →