Methodology

How we calculate your result

Every calculator on this site follows the same general sequence, with each state's own rate and rules filled in:

1. Start with the vehicle's price.
2. Subtract your trade-in allowance, in the states that let a trade-in lower the taxable amount; some states only allow this for a new or a used vehicle, and a few don't allow it at all, which is why the step can change the total differently from state to state.
3. Add the dealer's documentation fee to the taxable amount, in the states that tax it.
4. Multiply the taxable amount by the combined tax rate: the state rate, plus a local rate where the state has one, applied the way that state applies it (a flat percentage, a cap on how much of the price is taxed locally, or a minimum tax, depending on the state).
5. Add the title fee and registration fee we've confirmed for that state. A fee we haven't confirmed is left out and marked as such, never estimated.
6. For a loan calculator, work out the monthly payment from the total, your down payment, APR and loan term, using the standard amortizing-loan formula.

The "How it is calculated" section on every state's own page shows these same steps with that state's actual rate and rules filled in, not just the general pattern above.

Primary sources only

Every rate, rule and fee comes from an official source: a state's department of revenue, its motor vehicle agency, or the text of the state's own statute. We do not build a figure from an average of other calculator sites, and we do not carry a number forward just because it's common online.

What counts as a source

• A .gov page published by the state agency responsible for the tax or fee.
• The state's own statute or administrative code.
• An official fee schedule or dealer-facing manual published by the state's motor vehicle agency.

When we can't confirm a number

Sometimes an agency doesn't publish a clear figure, or two official-looking sources disagree and we can't resolve which is current. When that happens, the calculator marks that fee as not included rather than showing a guess, explains why, and lets you enter your own amount. We would rather show nothing than show a number we can't stand behind.

Structured, auditable data

Each state's rate, rule and fee lives in its own data file, separate from the page's design and wording. A correction to a number changes only that number, the page around it doesn't need to be rewritten, and the same data file drives both the written explanation and the calculator's math, so they can't quietly drift apart.

How often data is reviewed

Every state page shows when it was last reviewed. We re-check data on a regular schedule, and sooner when a tax or fee change is reported or when we find a conflict between sources while researching something else.

Report an error

Found a rate or fee that looks out of date? Contact us with a link to the official source, and see corrections for what happens next.