Auto Loan Calculator · Practical guide
Car Loan Calculator with Tax and Trade-In
Sales tax and trade-in value change the amount you actually finance — see the real payment before you sign.
At a glance
What You Actually Finance
The loan amount is not the sticker price. This calculator finances (vehicle price − down payment − trade-in) × (1 + sales tax rate). A $35,000 car with $5,000 down and 6% tax means borrowing ($35,000 − $5,000) × 1.06 = $31,800 — at 7% for 60 months that is $629.68 a month and $5,980.69 in interest.
Interactive tool
Auto Loan Calculator
Enter your own values, then compare the result with the examples below.
Auto Loan Summary
Adding a Trade-In
Take the same $35,000 car and $5,000 down, but now trade in a vehicle worth $8,000 at 6% tax:
- Financed amount: ($35,000 − $5,000 − $8,000) × 1.06 = $23,320
- Monthly payment at 7% for 60 months: about $461.77
- Total interest: about $4,386 — roughly $1,595 less than the no-trade-in deal
In states that tax only the price after trade-in, the trade-in saves you twice: once on the principal and again on the tax.
How Each Piece Moves the Payment
| Scenario ($35,000 car, 7% APR, 60 mo, 6% tax) | Financed | Monthly Payment |
|---|---|---|
| No down, no trade-in | $37,100 | $734.63 |
| $5,000 down | $31,800 | $629.68 |
| $5,000 down + $8,000 trade-in | $23,320 | $461.77 |
What Is Not Included
Registration, title, and dealer documentation fees are not part of this calculation. If you plan to roll them into the loan, add them to the vehicle price. Dealers sometimes quote a payment without tax or fees to make it look smaller — always compare the financed amount, not just the monthly number.
Frequently Asked Questions
Is sales tax charged on the price before or after my trade-in?
It depends on the state. Many states tax only the price after the trade-in credit; this calculator applies tax after subtracting both the down payment and trade-in.
Do I have to finance the sales tax?
No. You can pay tax and fees out of pocket at purchase. If you do, enter 0% in the tax field and your down payment as-is so the loan reflects only the net price.
What if I owe more on my trade-in than it is worth?
That is negative equity. If you roll it into the new loan, add the shortfall to the vehicle price so the financed amount reflects the debt you are carrying over.
Does a higher trade-in offer beat a lower sale price?
Only the net difference matters. Compare deals on price minus trade-in, then let the calculator show the payment for each combination.