Cash Back or Low Interest Calculator
Compare a manufacturer's cash rebate against a promotional low-interest financing offer to see which one actually saves you more money over the life of the loan.
Results from this calculator are estimates provided for general informational purposes only, based on formulas, rates, and standards commonly accepted as of 2026. Figures may differ slightly from other calculators or professional sources due to rounding methods, differing assumptions, or regional regulations, and rules may change over time. Always consult a qualified professional — such as a financial advisor, healthcare provider, or other relevant specialist — before making decisions based on these results.
Better Deal
Low Interest Rate
Saves you $1,612.05 over the life of the loan
Example
On a $30,000 vehicle with a $3,000 down payment, taking the $1,500 cash rebate and financing the rest at 6.5% costs $32,936.21 in total over 60 months, while skipping the rebate for 1.9% financing costs $31,324.16 in total. The low interest rate is the better deal by $1,612.05.
Cash Rebate — Total Cost
$32,936.21
Low Interest — Total Cost
$31,324.16
Cash Rebate — Total Interest
$4,436.21
Low Interest — Total Interest
$1,324.16
Total cost comparison over the loan term
What is a Cash Back or Low Interest Calculator?
When buying a new car, manufacturers frequently let buyers choose between two incentives: a cash rebate applied directly to the purchase price, or a promotional low (sometimes 0%) interest rate on financing. You almost never get both — taking the rebate usually means financing at the regular, higher rate, while taking the low rate means giving up the rebate entirely.
This calculator runs both scenarios side by side — same vehicle price, same down payment, same loan term — and tells you which option leaves you paying less in total, and by how much.
How the Comparison Is Calculated
Generally, it comes down to which amount is higher: the rebate amount, or the total interest saved by the lower rate. Each option is financed as a standard amortizing loan:
- P — loan principal (price minus down payment, minus the rebate if taken)
- r — monthly interest rate (APR ÷ 12)
- n — number of monthly payments (loan term in months)
The total cost of each option is the down payment plus every monthly payment made over the full term. Whichever total is lower is the better deal in dollar terms.
Cash Rebate: An Instant Discount
A cash rebate is an additional deduction on the purchase price of a car, generally ranging from a few hundred to a few thousand dollars. Rebates can be instant (applied immediately at signing) or mail-in (arriving four to eight weeks later). Rebates tend to be more widely available to buyers regardless of credit history, since they don't depend on a lender's approval of a special rate.
Low-Interest Financing: Cheaper Money, No Discount
Low-interest offers come directly from the dealer or manufacturer's captive finance arm — not as a preapproval from an outside bank or credit union — and typically require excellent credit to qualify. The lower rate reduces the total interest paid over the loan, which can outweigh a modest rebate, especially on larger loans or longer terms where interest compounds over more payments.
Watch Out for State Tax Rules on Rebates
Tax treatment of rebates varies by state. Some states tax the vehicle based on its original price before the rebate is applied, which effectively reduces the rebate's value. Many other states — including Alaska, Arizona, Delaware, Iowa, Kansas, Kentucky, Louisiana, Massachusetts, Minnesota, Missouri, Montana, Nebraska, New Hampshire, Oklahoma, Oregon, Pennsylvania, Rhode Island, Texas, Utah, Vermont, and Wyoming — do not tax cash rebates at all. Check your state's rules before assuming the full rebate amount reduces your taxable purchase price.
Example — Your Current Inputs
On a $30,000 vehicle with a $3,000 down payment, taking the $1,500 cash rebate and financing the rest at 6.5% costs $32,936.21 in total over 60 months, while skipping the rebate for 1.9% financing costs $31,324.16 in total. The low interest rate is the better deal by $1,612.05.
Additional Example — A Bigger Rebate Wins
On a $22,000 car financed for 48 months, a $2,500 rebate at a regular 7% APR costs about $21,750 in total, while a 0.9% low-rate offer on the full $22,000 costs about $22,940 in total. Here the larger rebate relative to the shorter loan term makes the cash rebate the better choice by roughly $1,190 — the opposite outcome from a longer, larger loan where the low rate usually wins.
About These Parameters
- Vehicle Price & Down Payment
- The vehicle price is the agreed purchase price before incentives. The down payment reduces the amount financed identically under both offers, so it doesn't change which option wins — but a larger down payment shrinks both loans and the total interest at stake.
- Cash Rebate
- The dollar amount knocked off the price if you decline the special financing rate. Typical manufacturer rebates range from a few hundred dollars on economy models to several thousand on trucks and SUVs during clearance events.
- Regular APR & Low APR Offer
- The regular APR is what you'd pay if you take the rebate; the low APR offer (often 0%–3.9%) is only available if you skip the rebate. The bigger the gap between the two rates, and the longer the loan term, the more the low-rate option tends to save.
- Loan Term
- The number of months you'll repay the loan. Longer terms give the interest-rate difference more time to compound, which usually tilts the outcome toward the low-interest offer on larger loans.
Frequently Asked Questions
Can I ever get both the rebate and the low interest rate?
Almost never. Manufacturers structure these as mutually exclusive incentives because they cost the automaker money in different ways — the rebate is a direct discount, while the low rate is a subsidized financing cost. A few rare regional promotions combine both, so it's always worth asking your dealer directly.
Which option is usually better on a short loan term?
The cash rebate tends to win on shorter loan terms, since there's less time for a lower interest rate to accumulate meaningful savings — the upfront discount has an immediate, guaranteed impact regardless of term length.
Does my credit score affect which offer I should pick?
Yes — low-interest promotional rates typically require excellent credit to qualify at all. If your credit doesn't qualify for the advertised low rate, the cash rebate combined with your actual approved rate may be the only real option, regardless of what this calculator shows for the promotional rate.
Should I also compare financing through my own bank or credit union?
Definitely. Outside lenders sometimes beat both dealer offers, especially if you have strong credit and the manufacturer's low-rate promotion doesn't apply to your chosen trim or model year. Run any outside preapproval rate through this same comparison against the cash rebate.