Cash Back Or Low Interest Calculator
Compare cash back rebates versus low interest financing offers on car purchases. Enter values for instant results with step-by-step formulas.
Formula
Total Cost = Monthly Payment x Term Months, where Payment = Loan x (r / (1 - (1+r)^-n))
The calculator computes the monthly payment and total cost for each option. For the cash back option, the loan amount is reduced by the rebate but charged a higher interest rate. For the low interest option, the full loan amount is financed at the promotional rate. The option with the lower total cost is the better deal.
Frequently Asked Questions
What is the difference between cash back and low interest financing?
Cash back and low interest financing are two mutually exclusive incentive offers that car manufacturers frequently provide to attract buyers. With the cash back option, you receive a lump sum rebate that reduces your purchase price, but you finance at the standard market interest rate offered by your bank or credit union. With the low interest option, the manufacturer subsidizes the interest rate, often offering rates as low as 0 to 2.9 percent APR, but you give up the cash rebate entirely. The key to choosing correctly is comparing the total cost of ownership under each scenario, including the interest you pay over the full loan term and the initial discount you receive.
Are there tax implications to consider with cash back rebates?
In most US states, manufacturer cash back rebates are not considered taxable income to the buyer because they are treated as a reduction in the purchase price rather than as income. However, the sales tax calculation varies by state. In some states, you pay sales tax on the full vehicle price before the rebate, while in other states the rebate reduces the taxable price. For example, if you buy a $35,000 car with a $3,000 rebate, some states calculate tax on $35,000 while others calculate it on $32,000. This difference can amount to several hundred dollars depending on your state sales tax rate, and it can slightly affect which option is the better overall deal. Check your specific state rules before making a final decision.
What happens if I pay off the low interest loan early?
If you pay off a low interest promotional loan early, you save on interest payments because the remaining months of interest charges are eliminated. However, this also reduces the total benefit of having chosen the low interest option over the cash back option. If you plan to pay off the loan significantly ahead of schedule, the cash back option often becomes the better choice because you capture the full rebate immediately and the interest savings from the low rate are reduced by the shorter payoff period. Most manufacturer financing programs do not have prepayment penalties, but you should verify this before signing. Some buyers strategically take the cash back option knowing they will make extra payments to pay down the higher-rate loan faster.
Can I combine cash back with other dealer discounts or manufacturer offers?
Manufacturer programs typically specify whether the cash back rebate can be combined with the low interest rate, and in most cases you must choose one or the other. However, cash back rebates can usually be combined with other types of incentives like loyalty bonuses for returning customers, military or first responder discounts, college graduate programs, and competitive conquest offers for switching from a rival brand. Each of these additional incentives may add $500 to $1,000 to the overall discount. Dealer-level discounts on the vehicle price are separate from manufacturer incentives and can always be stacked. The total package of negotiated price plus all eligible incentives determines your true out-of-pocket cost.
What is the difference between simple and compound interest?
Simple interest is calculated only on the original principal: SI = P × r × t. Compound interest is calculated on the growing balance — each period's interest is added to the principal before the next period is calculated. The formula is A = P(1 + r/n)^(nt), where n is compounding frequency. On a $10,000 investment at 8% over 20 years, simple interest yields $26,000 while annual compounding yields $46,610 — a 79% difference. More frequent compounding (monthly vs. annually) further accelerates growth, which is why high-yield savings accounts advertise APY (annual percentage yield) rather than the nominal rate.
Is my data stored or sent to a server?
No. All calculations run entirely in your browser using JavaScript. No data you enter is ever transmitted to any server or stored anywhere. Your inputs remain completely private.