Car Down Payment / Loan Split Calculator
See exactly how price, tax, trade-in and your down payment split into cash up front versus the amount you finance — and the monthly payment.
How it works
Tax = (price − trade) × tax% · Financed = price + tax − trade − down · Payment = amortize(financed, APR, term)
The out-the-door cost is the price plus sales tax; your trade-in and cash down payment reduce it, and whatever remains is financed. In most states the trade-in lowers the taxable amount, so a trade cuts both the loan and the tax bill. A bigger down payment shrinks the loan and the interest, and lenders often reserve their best rates for buyers who put more down.
Worked example
A $30,000 car with 7% tax on the full price adds $2,100. A 10% down payment is $3,000 and no trade-in, so you finance $29,100. At 6.5% over 60 months that is about $569 a month, with roughly $5,050 of total interest.
Frequently asked questions
How much should I put down on a car?
A common guideline is 20% on a new car and 10% on a used one — enough to offset first-year depreciation and avoid owing more than the car is worth. More down means a smaller loan, less interest and often a better rate.
Does a trade-in reduce sales tax?
In most states, yes — tax is charged on the price minus the trade-in value, so a trade lowers both the amount financed and the tax. A few states tax the full price regardless; this tool assumes the trade is deducted first.
Is the down payment before or after tax?
Here the down payment is a percentage of the vehicle price, paid in cash, while sales tax is added to the financed balance. You can raise the down payment percentage to cover the tax in cash instead.
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Educational estimate, not financial advice — real quotes, taxes and fees vary by lender, state and vehicle.