Auto Loan Calculator With Trade-In and Tax
Full car loan payment including trade-in value, negative equity, sales tax, dealer fees and down payment. The real number behind the financing offer.
A car loan calculator that does not include sales tax and trade-in value tells you about half the story. The dealer rolls those numbers into your monthly payment, so your calculator should too. This page links to the full auto loan calculator on this site, which handles trade-in, negative equity, sales tax and fees as separate line items.
What This Calculator Covers
- Vehicle price (negotiated, not MSRP)
- Cash down payment
- Trade-in value (dealer offer or private-sale price)
- Trade-in loan owed (if you still owe money on the trade)
- Sales tax rate (varies by state and county)
- Fees / title / registration
- Interest rate (from your pre-approval or dealer)
- Loan term (36 to 84 months)
How Sales Tax Works With Trade-In
Most US states allow your trade-in value to reduce the sales-tax base. If a $35,000 car has $7,000 of trade-in credit, in most states you pay tax on $28,000, not $35,000. At a 7% rate, that saves you $490.
A few states (California, Virginia, Michigan and others) tax the full purchase price regardless of trade-in. Check your state. Selling the trade privately and pocketing the cash usually gets you a higher net price but loses the tax break, so the math is closer than people think.
Negative Equity
If you owe more on the trade than it is worth, that gap is "negative equity" and rolls into the new loan. Example: trade worth $12,000 with $15,000 still owed leaves $3,000 of negative equity added to the new loan. Many buyers do not realize this until they see the new loan amount. Always check the trade-in payoff statement before signing.
Example Calculation
| Item | Amount |
|---|---|
| Vehicle price | $35,000 |
| Trade-in value | −$7,000 |
| Taxable amount | $28,000 |
| Sales tax @ 7% | +$1,960 |
| Fees | +$500 |
| Cash down | −$5,000 |
| Amount financed | $25,460 |
| At 7.5% APR over 60 months | $510 / month |
| Total interest paid | $5,140 |
| Total cost of ownership | $35,100 |
Use the Full Calculator
The Auto Loan Calculator handles every scenario described on this page. For the deeper math and worked examples, read the companion guide.