Compare a car cash rebate with low-interest financing using monthly payments, interest, tax, fees and total purchase cost for both offers.
Calculator
Illustrative rates; debt-free trade-in only.
Offer Comparison
Purchase Cost Details
| Metric | Cash rebate offer | Low-rate offer |
|---|
Cash rebate vs low-interest auto financing
A cash rebate lowers the amount you pay for the vehicle, while a lower financing rate reduces interest. This calculator compares two mutually exclusive offers on the same vehicle using the same term, cash-down budget and trade-in value. It shows each loan amount, tax estimate, upfront payment, monthly payment, total interest and total purchase cost. Starting inputs are illustrative, not current manufacturer offers.
Compare total purchase cost, not just interest
purchase cost = upfront cash paid + scheduled loan payments + trade-in value
net savings = higher purchase cost - lower purchase cost
Trade-in value is included because giving up a vehicle has economic value even though it is not a cash payment. It is not added to the monthly loan payment. The winner is the offer with the lower modeled purchase cost over the full term. Differences below half a cent are treated as a tie. An offer with less interest does not automatically save the full interest difference: declining a rebate also has a cost.
Worked rebate comparison
Consider a $50,000 car, $10,000 cash down, no trade-in, 60 months, $3,500 tax and $2,000 fees paid upfront. A $1,000 rebate with 5% financing leaves a $39,000 loan. The alternative has no rebate and a 2% rate on a $40,000 loan. Modeled monthly payments are about $735.98 and $701.11. The purchase costs are about $59,658.69 and $57,566.62. The low-rate offer saves about $2,092.06 overall, after accounting for the forgone rebate, not simply the difference between the interest totals. Calculations retain full precision before display rounding, so subtracting two already-rounded table values can differ by a cent. Lender payment rounding and the final installment may differ.
Tax and fee assumptions
The default model applies your entered tax rate to the vehicle price, with separate choices for whether the rebate or trade-in reduces that taxable price. Those checkboxes are assumptions, not a statement about your state. Taxable price cannot fall below zero. Fees are entered as one separate total and are not themselves taxed by this simplified rate model.
If the dealer quotes different tax amounts, select the quoted-tax mode and enter both amounts directly. This can represent a quote with exemptions, capped trade-in treatment or tax on fees without pretending a general checkbox reproduces every rule. The quoted amount replaces the calculated tax; it is not added a second time. No state tax rate or legal rule is automatically selected.
When tax and fees are financed, both increase the starting loan balance. Otherwise they increase upfront cash. Financing can lower today's cash requirement but add interest. Use written itemized offers to avoid counting a charge both in the vehicle price and in the separate fee field.
Loan and cash limits
The model uses level monthly payments at a fixed annual note interest rate divided by 12, with the first payment one month after financing. Do not substitute fee-inclusive APR for the note rate while also entering those fees separately. It supports whole-month terms from 1 through 600 months for mathematical comparison; that range does not mean lenders offer every term.
The rebate is applied immediately to the purchase, not received later by mail. If the cash-down budget exceeds an offer's remaining balance, only the amount needed is used and the unused cash is shown. A zero balance has no loan payment or interest. Trade-in value plus rebate cannot exceed the vehicle price in this model; cash payouts for excess trade credit are outside its scope.
Use a debt-free trade-in value here. A balance still owed on your current vehicle, negative equity, different negotiated vehicle prices, different terms, rate resets, early payoff, late fees and optional add-ons need a different or more detailed comparison. The auto loan calculator accepts an amount owed on a trade-in; the trade-in calculator can help separate an offer from payoff equity. Do not treat either alternative as an automatic comparison of two incentive packages.
Check the actual financing offers
The CFPB's guide to comparing auto loan offers recommends considering rate, term, amount financed and overall cost, not only the monthly payment. Compare lender disclosures, eligibility and all required charges before choosing an offer. This calculator does not approve credit or guarantee a promotion.
Frequently asked questions
Does zero-percent financing always beat a rebate?
No. A sufficiently large immediate rebate can lower total cost more than the interest saved. Compare both sets of inputs; a zero rate divides the remaining principal evenly over the term.
Why is the lower-interest saving different from the final saving?
One offer also includes a rebate and may have different tax. Net purchase-cost savings reflect those differences as well as interest. The details table separates them.
Can I use different tax amounts for each offer?
Yes. Choose the quoted-tax option. Check that each quote reflects the same vehicle, trade and fee assumptions.
Does this account for early repayment?
No. It assumes the loan runs to its stated term with no extra payments. The result also excludes running costs, resale value and the time value of money.