Methodology

Every figure on TagTally should be checkable by anyone. This page documents where the data comes from, how calculations are performed, and how often figures are re-verified. Individual calculator and data pages repeat the specific sources and verification dates for the numbers they show.

Data sources

Rates and fees are taken from primary sources only, in this order of preference:

• State statutes and administrative codes — the legal basis for vehicle sales/excise tax rates, trade-in credit rules, and statutory fee caps (including dealer doc fee caps where they exist).
• State departments of revenue / taxation — published vehicle tax bulletins, rate tables, and local (county or city) add-on rates.
• State motor vehicle agencies (DMV/MVD/BMV/RMV) — official fee schedules for title, registration, plate/tag, and EV or hybrid surcharges.

Secondary summaries — other calculator sites, dealer sites, or news articles — are not used as sources for rates. They are consulted only to notice discrepancies worth re-checking against an official source. Tables on this site are compiled from the primary sources above, not copied from any other compilation.

How figures are computed

• Out-the-door price = negotiated vehicle price + sales/excise tax + title fee + registration fee + plate/tag fee + dealer doc fee, applying each state's own base for the tax line.
• Tax base: where a state grants a trade-in credit, tax is computed on (price − trade-in value) per that state's rule, including partial credits and dollar caps where they apply. Rebate treatment (taxed vs. untaxed) follows each state's published rule.
• Local rates: where county or city add-ons apply, pages state whether a figure uses the state minimum, a population-weighted typical rate, or a user-selected county — and label which one it is.
• Value-based registration (VLT states): states that tax vehicle value at registration are computed with that state's published assessment formula, shown step by step on the relevant page.
• Doc fees: where a state caps the fee, the cap is cited to statute. Where uncapped, pages show a typical statewide range and mark it clearly as market data, not law.

Each calculator page publishes its formula in plain text with variable definitions and a worked example with real numbers, so results can be reproduced by hand.

Rounding and presentation

Calculations are carried out unrounded and displayed to the cent for line items and totals. Percentage rates are shown as published by the state (typically to two or three decimal places). Where an official source publishes a range rather than a single figure, the range is shown rather than a midpoint presented as fact.

Update policy

• Annual full review: every state's rates and fees are re-verified against primary sources once a year, ahead of the main legislative-effective dates (most rate changes take effect January 1 or July 1).
• In-year corrections: states with known pending legislation are re-checked when the change takes effect; reader-reported discrepancies are re-verified against the primary source, typically within days.
• Dating: every data page carries the date its figures were last verified. The sitemap's last-modified dates reflect content changes.

Independence

TagTally has no commercial relationship with any dealer, lender, or state agency. No one pays to have a figure presented differently. Advertising, if shown, is clearly separated from data and has no influence on the numbers.

Limits

Figures here are estimates for general information, not financial, tax, or legal advice, and not a promise of what you will pay. Final amounts come from your state agency and your contract. Found something out of date? Report it with the official source and it will be re-verified.