How out-the-door price is calculated
Advertised price is not what you pay. OTD rebuilds the finance-office stack so two quotes can be compared honestly.
Line by line
Start with negotiated vehicle price. Subtract trade-in allowance for cash effect. Compute tax on a taxable base that depends on the state’s trade-in credit rule (full, partial, or none). Add title fee, a midpoint of the typical annual registration band, and the dealer doc fee you were quoted.
TagTally’s estimator follows that order. Local tax uses the midpoint of a published add-on band when the state allows city/county stacks — your ZIP can sit outside that band.
What we refuse to invent
Schedule-based excise systems (for example some value-and-MPG formulas) are labeled instead of faking a single percentage. EV surcharges, specialty plates, and inspection programs are not fully modeled — ask the DMV schedule if those apply.
How to use it in a negotiation
Force every dealer to restate tax, title, registration, plate, and doc fee on separate lines. If their tax line diverges from the table after adjusting for county and trade-in, ask which rate table they used.
- Same car, same ZIP, two dealers → compare OTD, not monthly payment.
- Monthly payment hides term, APR, and backend products.
On this bay
General information, not personalized advice.