Start with the vehicle, not the interest statement
A bank statement showing interest is only one part of the qualification test. The law and the existing T4 methodology focus on the vehicle and the purchase loan as well as the amount paid. A used vehicle, a lease, a business-use arrangement, or a vehicle assembled outside the United States can fail even when the lender reports interest.
“New” means the vehicle's original use starts with the taxpayer. Buying a model that is new to you is not enough if it was previously titled or used. The purchase must also occur after December 31, 2024, which is why the calculator's eligible years begin with 2025.
The T4 copy describes qualifying passenger vehicles under 14,000 pounds GVWR and lists cars, minivans, vans, SUVs, pickups, and motorcycles as potential categories. Potential is not automatic eligibility: personal use, final assembly, first lien, and the other conditions still need to be satisfied.
Qualification checklist
Before using the deduction estimate, walk through each item below and save the document that supports it. The checklist is deliberately factual; it is not a promise that a lender's product or a particular model qualifies.
- New vehicle: the original use begins with you.
- Purchase date: the vehicle is purchased after December 31, 2024.
- Personal use: the vehicle is used personally rather than solely for business.
- US final assembly: final assembly occurred in the United States.
- Purchase indebtedness: the debt finances the purchase and is secured by a first lien.
- Vehicle category and weight: it fits the applicable passenger-vehicle description and the under-14,000-pound GVWR condition.
- VIN reporting: the vehicle identification number is available for the federal return.
How to check the assembly plant
The window sticker is a useful first document because it may identify the final assembly location. When the sticker is unavailable or unclear, use the NHTSA VIN Decoder at vpic.nhtsa.dot.gov/decoder/ and look for the assembly-plant information associated with the VIN. Keep a copy of the result with the purchase documents.
A VIN decoder lookup is evidence for the assembly question, not a replacement for the other requirements. It does not decide whether the car was new to you, whether the loan is purchase indebtedness, or whether personal-use rules are met. If the VIN result is incomplete, ask the dealer or manufacturer for a written clarification before relying on the deduction.
Leases are a separate financing arrangement. The T4 FAQ says the statute covers interest on purchase indebtedness secured by a first lien, not lease financing. A lease payment should therefore not be entered as qualified loan interest in the calculator.
What the auto-loan calculator does next
Once qualification is established, the calculator amortizes the amount financed and totals interest for years one through five. It caps the qualified amount at $10,000 per year for 2025–2028, applies the MAGI phase-out, and estimates federal tax saved using the shared bracket walk. If the qualification checkbox is off, the deduction is zero and the result shows a warning instead of treating the loan as eligible.
Keep the purchase contract, financing agreement, VIN record, window sticker, and interest statements together. Those records let a preparer check the facts behind the arithmetic and distinguish a qualifying purchase loan from a different vehicle expense.