Financial research concept

Auto Finance Interest Margin

Auto finance interest margin is interest and fee income less the funding interest expense associated with the auto-loan portfolio.

By Lee BaileyPublished Sep 25, 2026

Research context

See what supports this page, how current it is, and where comparable or historical context is available.

Research date: Sep 25, 2026Use the dated article and cited sources for the definition, examples, and stated limitations.
Operating-model context: 23 connected conceptsPart of the reviewed Used Auto Retail & Finance Economics; issuer definitions remain distinct where disclosed.
Company examples: 1 reviewed companyRelationships reflect supported examples, not a normalized cross-company KPI ranking.

CarMax example
What drives the margin
Not profit after credit losses
Part of the Used Auto Retail & Finance Economics
See It in Company Research
Continue Research

Auto finance interest margin is the dollar spread between interest and fee income earned on auto loans and the interest expense associated with funding those loans.

Interest margin = interest and fee income − interest expense

CarMax example

CarMax Auto Finance reported fiscal 2026 interest and fee income of $1.8642 billion, interest expense of $769.2 million, and total interest margin of $1.0950 billion.

What drives the margin

The dollar result depends on both balance-sheet scale and spread economics. It can change because of:

average loans outstanding;
customer contract rates;
funding costs;
origination mix;
loan sales; or
portfolio seasoning.

That is why the dollar margin should be paired with interest margin rate.

Not profit after credit losses

Interest margin is measured before CarMax's provision for loan losses and direct CAF expenses. It therefore should not be read as finance-segment profit.

A wider lending spread can still coincide with lower Auto Finance Income if credit costs rise enough.

Primary source: CarMax fiscal 2026 Form 10-K.

Part of the Used Auto Retail & Finance Economics

Connect used-vehicle demand, pricing, sourcing, digital transaction mix, wholesale disposition, operating leverage, finance penetration, lending spread, and credit performance across an integrated used-auto retailer.

Browse the full operating model in Company Analysis →

Where this concept fits

Finance origination, spread, and credit performanceCurrent relationship
Net finance penetration and net auto loans originated show how retail sales feed the lending book, interest margin and its rate show lending spread economics, finance income shows the resulting segment contribution after included credit and direct costs, and past-due, net credit loss, and recovery rates show portfolio performance and loss severity.
Auto Finance Average Recovery Rate Auto Finance IncomeAuto Finance Interest MarginCurrent conceptAuto Finance Interest Margin Rate Net Auto Loans Originated Auto Finance Net Credit Loss Rate Auto Finance Net Penetration Rate Auto Finance Past-Due Account Rate
Retail volume, pricing, margin, and operating leverage
Retail unit sales and comparable-store unit growth show demand, average selling price shows transaction value, used-vehicle gross profit per unit shows front-end merchandising margin, and SG&A per total unit plus SG&A as a percent of gross profit show how transaction economics convert through the retailer's overhead base.
Used Auto Comparable Store Unit Sales Growth Used Auto Retail Average Selling Price Used Auto Retail Unit Sales Used Auto SG&A as a Percent of Gross Profit Used Auto SG&A per Total Unit Used-Vehicle Gross Profit per Unit
Sourcing, digital channel mix, and wholesale disposition
Vehicle purchases from consumers and dealers show inventory sourcing, digitally enabled, omni, and online sales rates show how customers move through the transaction funnel, extended protection plan revenue adds attached-product economics, and wholesale units, selling price, and gross profit per unit show the disposition path for vehicles sold to dealers.
Digitally Enabled Transaction Rate Extended Protection Plan Revenue Used Auto Omni Sales Rate Used Auto Online Retail Sales Rate Vehicle Purchases from Consumers Vehicle Purchases from Dealers Used Auto Wholesale Average Selling Price Used Auto Wholesale Gross Profit per Unit Used Auto Wholesale Unit Sales

See It in Company Research

These companies are examples of how the concept is reported or discussed in public filings. Definitions can differ by issuer; these links open company research rather than a normalized metric comparison.

KMXOpen operating-model research →23 of 23 reviewed concepts in Used Auto Retail & Finance EconomicsFinance origination, spread, and credit performance8 of 8 bridge concepts supportedContinue through this bridge:Auto Finance Average Recovery Rate Auto Finance Income Auto Finance Interest Margin Rate Auto Finance Net Credit Loss Rate Auto Finance Net Penetration Rate Auto Finance Past-Due Account Rate Net Auto Loans Originated

Continue Research

Continue from the concept into the Grizzly Bulls research surface that best matches the next question. These links are research continuations, not recommendations or required steps.

Continue Research

Compare public companies

Compare valuation and company research across the reviewed Grizzly Bulls stock universe.

Continue research

Explore more topics in the Financial Research Encyclopedia.