Source selection
We prioritize primary material: state statutes and regulations, department of revenue guidance, motor-vehicle agency fee schedules and forms, and other government publications. Secondary sources may help identify a question, but they do not replace an available primary source for a material rule.
Research and verification
State topics are researched separately because tax bases, residence rules, fee schedules, and transaction paths differ. Pages identify source agencies and display the verification date used for that content. A verification date records when a source review was performed; it is not a guarantee that a rule cannot change later.
When a rule depends on facts the calculator does not collect, or an amount cannot be supported confidently, the tool may exclude it or describe the limitation instead of guessing.
Conflicts, rounding, and estimates
When official sources appear inconsistent, we preserve the relevant distinction, explain the choice made by the calculator, and link the sources where practical. Calculators use deterministic arithmetic for the supported inputs; the result may still differ from an agency or dealer amount because of proration, local jurisdiction, vehicle classification, documents, exemptions, transaction-specific interpretation, or rounding instructions.
Examples are generated from the corresponding existing calculator engine where available. Explanatory writing clarifies the rule but does not expand the engine's supported transaction scope.
Corrections and independence
When a possible error is identified, the relevant claim and underlying primary source should be reviewed, and a confirmed correction should be made to the affected page with its verification date updated as appropriate. There is not currently a public contact form or published contact address on this site, so we do not imply that a particular submission channel is available.
Calculator outputs are not influenced by paid placement. CarBuyerKit is independent of government agencies and dealerships; no paid relationship is represented as affecting a rule or estimate.
For how calculations are structured, see Calculator Methodology.