Calculation and Content Methodology

Calculation order

1. Start from the entered selling price.
2. Apply dealer discounts and confirmed taxable price reductions.
3. Add dealer fees and taxable products to the taxable measure where the selected engine does so.
4. Subtract a qualifying trade allowance.
5. Calculate regular and special taxes.
6. Add government charges and non-taxable products.
7. Subtract a cash rebate from the amount paid unless the user confirms another treatment.
8. Show trade equity and down payment after OTD to calculate the amount to fund.

How calculation confidence is labelled

Nine detailed state engines use versioned official-source rules: Florida, Texas, Washington, California, Georgia, North Carolina, Illinois, New York and Tennessee. Fixed statewide rules are calculated directly. Location-, vehicle- and transaction-specific values remain visible inputs instead of being replaced with false precision. The national path is explicitly labelled as a custom-rate estimate.

Rounding

Displayed monetary results are rounded to cents after the applicable formula step. Real dealer or agency systems may round component lines differently.

Quote classification

The checker uses label-based categories and neutral review flags. It does not decide that a fee is illegal, mandatory or negotiable because those conclusions can depend on law, disclosures and transaction facts.

Guide editorial method

Guides begin with the buyer’s decision or document question, define the relevant terms, show how the figures connect, provide a worked example and end with questions to ask before agreeing. Repeated legal conclusions are avoided when rules depend on the state, contract or transaction type.

Source hierarchy

Federal agencies, state revenue departments, motor-vehicle agencies and published statutes or administrative guidance take priority over dealer pages, rate aggregators and unsourced summaries. Source dates are shown separately for calculator rules and guide content.

Update policy

Calculator rules are maintained with effective-date context, review date, public source and regression coverage. Date-sensitive thresholds, such as Washington luxury-tax deductions, are selected from the purchase date rather than only a year label. Informational guides are reviewed when an agency changes a cited rule, when a major program expires or when a page’s examples no longer match the current buying environment. Review material changes in the public fee update log and verify the underlying agencies in the official source registry.