A dealer offers you two things and you can have exactly one: 0% financing, or $3,000 cash back.
This is not a preference question. It has an arithmetic answer, and the answer is a single number.
On a $38,000 car with $4,000 down over 60 months, the two offers cost exactly the same if your own bank would lend at 3.70%. Above that rate the 0% wins. Below it, take the money.
A note before you start. This is general education, not financial advice. Every figure is computed by this site's own APR-versus-rebate engine. Purchase prices, rebates and rates are illustrative — the point is the method, and your own numbers will give a different break-even.
1. Why you cannot have both
Promotional financing is paid for by the manufacturer. A captive finance arm lending at 0% is forgoing interest it would otherwise earn, and that forgone interest is a marketing cost — the same budget the cash rebate comes out of.
So the two offers are alternative ways of spending the same subsidy on you, which is why they are almost never combined and why the choice is real rather than a trick.
What that means practically: the offers are close in value by design. The manufacturer has sized them to be roughly equivalent for a typical buyer. You are looking for the cases where you are not the typical buyer — and the break-even rate is how you find out.
Run the two offers on your own numbers2. The break-even rate
Here is the same $38,000 purchase against a range of outside rates:
| Your own bank's rate | 0% offer, total cost | Rebate offer, total cost | Winner | By |
|---|---|---|---|---|
| 4% | $38,000 | $38,255 | 0% APR | $255 |
| 5% | $38,000 | $39,100 | 0% APR | $1,100 |
| 6% | $38,000 | $39,959 | 0% APR | $1,959 |
| 7% | $38,000 | $40,830 | 0% APR | $2,830 |
| 8% | $38,000 | $41,714 | 0% APR | $3,714 |
| 9% | $38,000 | $42,611 | 0% APR | $4,611 |
The break-even is 3.70%. Every row above it favours the promotional rate, and the advantage grows by roughly $870 for each additional percentage point.
Two things worth noticing in that table.
The 0% column never moves. $38,000 is $38,000, because there is no interest. The entire comparison is about how expensive your alternative financing is.
And the monthly payments barely differ. At 7% the two payments are $567 and $614 — a $47 gap. That $47 is the whole visible difference, and it conceals $2,830 of total cost. A buyer comparing monthly payments alone is looking at 1.7% of the number that matters.
3. The break-even moves with the rebate
Bigger rebate, higher break-even — because the rebate has to be worth more to beat free money.
| Rebate offered | Break-even rate | Winner at a 7% outside rate | By |
|---|---|---|---|
| $1,000 | 1.18% | 0% APR | $5,206 |
| $2,000 | 2.41% | 0% APR | $4,018 |
| $3,000 | 3.70% | 0% APR | $2,830 |
| $4,000 | 5.04% | 0% APR | $1,642 |
| $5,000 | 6.44% | 0% APR | $454 |
At $5,000 the offers have almost converged — $454 apart on a $38,000 purchase, which is inside the range that a single negotiation round could move.
The rule of thumb that falls out of this table: on a purchase of roughly this size and term, each $1,000 of rebate is worth about 1.3 percentage points of break-even.
And the practical reading is simpler than it looks. A small rebate almost never beats 0%. A $1,000 rebate only wins if you could borrow at under 1.18%, which essentially nobody can. The choice is only genuinely live once the rebate is large relative to the car's price.
4. The break-even moves with the term, in the direction people do not expect
| Loan term | Break-even rate | 0% advantage at a 7% outside rate |
|---|---|---|
| 36 months | 6.10% | $459 |
| 48 months | 4.60% | $1,632 |
| 60 months | 3.70% | $2,830 |
| 72 months | 3.09% | $4,053 |
| 84 months | 2.65% | $5,301 |
The longer the loan, the more the 0% is worth.
That is straightforward once stated — a longer term means more months of interest avoided — but it cuts against the usual advice, which is that long car loans are bad. Both things are true at once, and holding them together is the useful part:
A long term is bad because it keeps you in negative equity for longer and encourages buying more car than you can afford. All of that still applies.
But if you are taking a long term anyway, the 0% offer is worth far more to you than it is to someone taking 36 months — $5,301 against $459.
The wrong conclusion is "take the 0% and stretch the term to 84 months to maximise the benefit." You would be maximising a saving on interest you only owe because the term is long. The right comparison is always against the term you would have chosen regardless.
5. The four things that break the comparison
The break-even is arithmetic. Getting the inputs wrong is where the money is actually lost.
You do not qualify for the 0%
Promotional financing is typically reserved for the top credit tier. A buyer who assumes they will get 0%, negotiates on that basis, and is then offered 4.9% at the desk has lost the rebate as well — because the choice was made before the rate was confirmed.
Get the rate approved in writing before you decide. This is the single most common way this comparison goes wrong.
The rebate is negotiable and the rate is not
A cash rebate is a fixed manufacturer program. The negotiated price of the car is separate, and taking the rebate does not stop you negotiating the price.
But a buyer who takes the 0% sometimes finds the dealer less willing to move on price, because the finance subsidy has already been spent on them. If that happens, the price difference belongs in the comparison — and this article's table does not include it.
You compare different terms
The engine behind this article applies the same term to both offers deliberately. Comparing a 0% over 36 months against a rebate over 72 months is not a comparison of the offers; it is a comparison of two different loans.
Fix the term first, then choose the offer.
You forget you can do both, sequentially
Take the rebate, finance at your own bank, and then pay the loan off early and the interest you actually pay is less than the table assumes. That improves the rebate side.
Take the 0% and there is nothing to pay off early — the money is already free, so early repayment saves nothing at all. This asymmetry favours the rebate for anyone who genuinely will pay early, and it is worth a percentage point or so of break-even for a buyer who is disciplined about it.
6. Most promotional rates are not 0%
"0% APR" is the headline. The offer on the vehicle you actually want is more often 1.9% or 2.9%, and that changes the answer considerably.
Same $38,000 purchase, same $3,000 rebate, same 60 months, against a 7% outside rate:
| Promotional rate | Break-even rate | Winner at 7% | By |
|---|---|---|---|
| 0% | 3.70% | Promotional | $2,830 |
| 0.9% | 4.63% | Promotional | $2,047 |
| 1.9% | 5.66% | Promotional | $1,163 |
| 2.9% | 6.70% | Promotional | $265 |
| 3.9% | 7.73% | Rebate | $647 |
| 4.9% | 8.77% | Rebate | $1,574 |
Every percentage point on the promotional rate raises the break-even by roughly one point — which makes sense, and makes the rule easy to carry.
The useful threshold is right around 2.9%. At a 7% outside rate the two offers are $265 apart, which is inside the noise of a single negotiation. Above roughly 3% promotional, the rebate starts winning outright.
Two practical readings.
A 0.9% or 1.9% offer is still strong. It is not 0%, and it still beats a $3,000 rebate comfortably for anyone borrowing at 7%. Do not dismiss a low-but-not-zero rate as a lesser version of the headline — at 1.9% the promotional offer is $1,163 ahead.
But a 3.9% "special rate" against a decent rebate is usually the worse deal, and it is presented in exactly the same language as the 0%. The word "special" carries no arithmetic.
And the same rule applies as everywhere else in this article: it depends on your outside rate. A buyer who can borrow at 4% flips several of those rows. Run yours.
7. What to do at the desk
Five steps, in order.
Get your own rate first, before you shop. A credit union or bank pre-approval takes an afternoon and it is the number the entire comparison runs on. Without it you cannot compute a break-even and you are negotiating blind.
Negotiate the price of the car before mentioning either offer. The price is the largest number and it is the one most affected by what the dealer thinks you want.
Then ask which offers you actually qualify for, in writing. Not "what are the offers" — which ones apply to you, at your credit tier, on this vehicle, this month.
Compare on total cost, not monthly payment. Section 2: the payments differed by $47 and the totals by $2,830.
And run the break-even at the term you actually want. Section 4 is why: the same two offers give a 6.10% break-even at 36 months and 2.65% at 84.
8. How the trade-in changes it
A trade-in interacts with both offers, and in two states' worth of cases it interacts with the tax as well.
On the financing side, the effect is symmetrical and small. A trade-in reduces the amount financed under either offer, which shrinks the absolute gap between them without moving the break-even rate at all. The break-even is a property of the rebate and the term, not of how much you borrow.
On the tax side it is neither symmetrical nor small.
In the 41 states that credit a trade-in against the taxable price, the trade reduces sales tax under both offers equally — so again it does not move the comparison.
But a rebate can be treated differently from a trade-in for tax purposes, and states differ on whether a manufacturer rebate reduces the taxable price. Where a rebate does not reduce it, taking the rebate is worth slightly less than its face value in after-tax terms.
This site's vehicle dataset records trade-in treatment per state — and four states with a sales tax give no credit at all — but it does not yet record rebate tax treatment per state. So this article does not make a fifty-state claim about it, and the tables above exclude tax on both sides so the comparison stays like-for-like.
What to do about it in practice:
Ask the dealer to show both deals as out-the-door totals, with tax computed. That folds every state-specific treatment into one comparable number without either of you needing to know the rule.
And negotiate the price and the trade-in before you choose the offer. Both are settled independently of which financing you take, and settling them first stops the offer choice being used to reopen them.
9. When the rebate genuinely wins
This article has so far shown the 0% winning in every row of every table, which is a function of the illustrative rates rather than a general law. Here is when the rebate is the right answer.
When you can borrow cheaply. Below the break-even rate the rebate wins outright — and a credit union member with excellent credit can sometimes beat 3.70%, particularly on a shorter term.
When you are paying cash. A cash buyer cannot use 0% financing at all, so the rebate is the only offer with any value to them. This is the clearest case and it is frequently overlooked — the rebate is worth its full face value, immediately.
When the rebate is large relative to the price. Section 3: a $5,000 rebate on a $38,000 car pushes the break-even to 6.44%, which is within reach of ordinary financing.
When you will pay the loan off early. Section 5's fourth point. The rebate is banked immediately; the 0% benefit only accrues month by month.
And when taking the rebate lets you finance less. A rebate applied as a down payment reduces the amount financed, which reduces the risk of negative equity — and that is a real benefit that does not appear anywhere in a total-cost comparison.
10. A worked decision, start to finish
Putting the whole thing together on one purchase.
The car is $38,000. You have $4,000 down and want 60 months. The manufacturer offers 0% APR or $3,000 cash back.
Step one: get an outside rate. Your credit union quotes 6.4%.
Step two: find the break-even. With a $3,000 rebate over 60 months it is 3.70%.
Step three: compare. 6.4% is above 3.70%, so the promotional rate wins. Running it exactly, the 0% offer costs $38,000 against $40,306 — about $2,300 better.
Step four: confirm you qualify, in writing, before conceding the rebate. If the desk comes back with 2.9% rather than 0%, the break-even moves to 6.70% — and at your 6.4% credit union rate the rebate now wins by a couple of hundred dollars. The decision reverses on that one line.
Step five: negotiate the price regardless. Neither offer is affected by what you pay for the car, and the price is worth more than the difference between the two offers in most negotiations.
The thing to notice about that sequence: the arithmetic took thirty seconds and the answer changed twice — once when the outside rate came in, once when the actual promotional rate did. Neither number was available before asking for it, and both were decisive.
Which is the article in one line: this is a computable question, and the inputs are things you have to go and get.
Frequently asked questions
Is 0% financing always better than a rebate? No. There is a break-even rate — the rate at which both offers cost the same. On a $38,000 car with $4,000 down, a $3,000 rebate and 60 months, it is 3.70%. If you can borrow below that, take the rebate.
How do I work out my own break-even? Run both offers over the same term on this site's calculator. The break-even is the outside rate at which the totals match; above it the promotional rate wins, below it the rebate does.
Why do the monthly payments look so similar? Because most of the difference is in total cost rather than in the payment. At a 7% outside rate the payments differ by $47 and the totals by $2,830 — comparing payments alone shows you under 2% of the decision.
Does a longer loan make 0% financing more valuable? Yes — the break-even falls from 6.10% at 36 months to 2.65% at 84, because a longer term means more interest avoided. That is not a reason to lengthen the term; compare at the term you would have chosen anyway.
Can I take the rebate and still negotiate the price? Yes. The rebate is a fixed manufacturer program and the price is separate. Be aware that a dealer may be less flexible on price when the manufacturer has already subsidised your financing.
What if I am paying cash? Take the rebate. Promotional financing has no value to a cash buyer, so the rebate is the only offer worth anything — at its full face value.
What if I plan to pay the loan off early? That favours the rebate. The rebate is banked at signing, while the benefit of a 0% rate only accrues over the months you actually hold the loan.
What is the commonest mistake? Choosing before the rate is approved. Promotional financing is usually restricted to the top credit tier, and a buyer who assumes they qualify, forgoes the rebate, and is then offered 4.9% has lost both.
What to do next
Get a pre-approval, fix the term, then compute the break-even. It is one number and it decides the question.
- Auto loan calculator — both offers, your own numbers.
- The four states that tax your trade-in — the other number that is not in the advertised price.
- The origination fee that makes a 0% loan cost money — when 0% is not 0%.
- Buying or leasing a car in the USA in 2026 — the full fifty-state picture.
Every figure on this site is sourced and dated. How we source every number.
All figures are computed by this site's own APR-versus-rebate engine, which applies the same term to both offers and compares total cost — payments plus down payment — rather than monthly payment. Purchase prices, down payments, rebate amounts, terms and outside rates used throughout are illustrative round numbers chosen to demonstrate the method; your own break-even will differ. The comparison does not include sales tax, title, registration or documentation fees, which apply to both offers and are covered separately in this site's state calculators; nor does it account for any difference in negotiated price between the two offers. Promotional financing eligibility is set by the lender and is typically restricted to the highest credit tiers. This is general education and not financial advice.