Used Car Dealer Taxes: Floor Plan Interest, Form 8300 for Cash Deals, Buy-Here-Pay-Here Installment Sales, and Inventory That Depreciates on the Lot

A used car dealer sells inventory it borrows to hold, and the return follows the vehicle from the auction to the note. The inventory — specific identification and the write-down: each vehicle is inventory, identified by its VIN at its cost (the auction or trade-in price plus the buyer's fee, the transport, and the reconditioning — the parts and labor to make it saleable — capitalized into the vehicle), and cost of goods sold is the specific vehicle's cost when it's sold; closing inventory is the vehicles on the lot at year-end at cost — or at the lower of cost or market (a dealer may write down a vehicle whose market value has fallen below its cost to that market value — the vehicle's actual wholesale value at year-end, documented with an official used vehicle guide's average wholesale value — the market the IRS accepts under Rev. Rul. 67-107 — not the dealer's own lower estimate), which lets the dealer recognize the lot's depreciation before the vehicles are sold; the method is elected and applied consistently. The floor plan — the financing: dealers finance inventory through a floor plan line (a lender advances the vehicle's cost at purchase, the dealer pays interest monthly and repays the principal when the vehicle sells, with curtailments — required principal payments — as a vehicle ages); the floor plan interest is deductible, and it has a special place in the business interest limitation (section 163(j)): floor plan financing interest is deductible in full regardless of the limitation — the limitation's adjusted-taxable-income cap doesn't apply to it — but a dealer that deducts floor plan interest under that exception can't use bonus depreciation on its other assets (the trade-off applies only in a year the exception is actually needed — total business interest above 30 percent of adjusted taxable income, which for tax years beginning after 2024 is again computed before depreciation and amortization; small dealers under the US$32 million gross receipts threshold are exempt from the limitation entirely and keep both). The sale — three ways to pay. Cash: a vehicle bought with more than US$10,000 in cash (currency, and in a vehicle sale cashier's checks, money orders, and bank drafts of US$10,000 or less — the designated reporting transaction rule) triggers Form 8300 — filed within fifteen days of the receipt, with the buyer's identification, and a written statement to the buyer by January 31; related payments within twelve months aggregate (a US$6,000 down payment and a US$5,000 payment on the same vehicle); structuring (the buyer splitting payments to avoid the threshold) is itself reportable and a crime to assist; a dealer that misses Forms 8300 faces per-return penalties and, for intentional disregard, much larger ones — the IRS examines dealerships for Form 8300 compliance specifically. Lender financing: the buyer finances through a bank, credit union, or finance company that the dealer arranges — the lender pays the dealer the amount financed (the vehicle's price, the taxes and fees, the add-ons) within days, and often pays the dealer a "dealer reserve" or participation (the difference between the rate the lender offers the buyer and the lender's buy rate, or a flat fee — income to the dealer when received, with the lender's chargeback of the reserve if the loan pays off early as a reduction when charged back). Buy-here-pay-here — the dealer finances: the dealer sells the vehicle on its own installment contract (a down payment and weekly or biweekly payments over two to four years at a high rate, secured by the vehicle, often with a GPS tracker and a starter interrupt), holding the note; for tax purposes, a dealer's sales of personal property it regularly sells are dealer dispositions — the installment method is not available (section 453(b)(2) and (l) — a disposition of personal property by a person who regularly sells that type of property on the installment plan is a dealer disposition, so the entire gain is reported at sale, not as payments are collected), so the gross profit is income in the year of the sale even though the dealer collects it over years, and the interest is income as it accrues or is received; the bad debts (repossessions, charge-offs) are the dealer's largest cost — a repossession is the note's worthlessness to the extent the repossessed vehicle's value (brought back into inventory at its fair market value) doesn't cover the balance, with the bad debt deduction for the shortfall (the bad debt guide — an accrual-basis item, since the sale was reported); some BHPH dealers sell the notes to a related finance company (a structure with its own tax analysis — the discount's arm's-length pricing, the finance company's substance, and the related-party loss rules) — the mark-to-market method of section 475 isn't an alternative, because notes from the sale of the dealer's own vehicles are "nonfinancial customer paper," excluded from the definition of a security even when a related finance company holds them; the BHPH dealer's return is dominated by the notes receivable, the reserve for bad debts (not deductible until specific charge-offs — the reserve method isn't allowed for tax), and the repossession accounting. The add-ons: service contracts (extended warranties) sold with the vehicle — if the dealer sells a third-party administrator's contract, the dealer's commission (the markup it keeps) is income, and the portion remitted to the administrator is not; if the dealer is the obligor on its own service contract, the advance payment's deferral under the service warranty rules (Rev. Proc. 97-38's service warranty income method — for an accrual-method dealer that insures its obligation with an unrelated insurer within 60 days, the insured portion of the price, plus an imputed-income amount, is included ratably over the shorter of the contract's term or six years) applies; GAP insurance and credit life products (the dealer's commission is income; the premium remitted is not — the insurance agent deductions guide's commission logic, with state licensing for the dealer's F&I staff), the documentation fee (income — capped in some states), and the dealer-installed accessories (sales, with their cost). Sales tax on vehicles: the state's motor vehicle sales tax is collected by the dealer at the sale (and remitted with the title and registration), computed on the price less a trade-in allowance in most states (a trade-in credit reduces the taxable price — some states don't allow it), with the add-ons' taxability varying (service contracts taxable in some states, exempt in others); the dealer buys its inventory for resale without tax (the dealer's license is its resale credential). The dealer license and the compliance: the state's dealer license, the surety bond, the dealer plates, the title and registration processing, the odometer disclosures, the Federal Trade Commission's Used Car Rule (the Buyers Guide window sticker — as-is or warranty disclosure on every vehicle), the Safeguards Rule for customer financial data (the dealer is a financial institution under it — a written information security program), the Truth in Lending disclosures for dealer financing, and the state's BHPH licensing (a sales finance or installment lender license) — all deductible. Staff: salespeople (commissioned — employees on the dealer's lot selling its inventory; the per-car "flat" and the percentage of gross), the F&I manager, the reconditioning technicians (the detailers and mechanics — employees, or a sublet shop), the BHPH collections staff; the auction buyers (employees or independent buyers paid per car — the classification follows control). Entity and the QBI deduction: a used car dealership is not a specified service trade — the QBI deduction applies at every income (the used car dealer entity guide). The bookkeeping: the inventory ledger by VIN with cost, reconditioning, and the year-end valuation; the floor plan by vehicle with interest and curtailments; deals by type (cash with the Form 8300 log; financed with the reserve and chargebacks; BHPH with the notes, the payments, the interest, the repossessions, and the charge-offs); add-on income separated from remittances; sales tax by deal; the dealer license and compliance file. The errors: Forms 8300 missed on cash deals (the IRS's dealership focus); BHPH sales reported on the installment method (not allowed for dealers); a bad debt reserve deducted (specific charge-offs only); reconditioning expensed rather than capitalized into the vehicle; the service contract's full price booked as income when most is remitted; and the floor plan interest's bonus-depreciation trade-off missed.

Key takeaways

• Each vehicle is inventory at its specific cost — auction price, fees, transport, and reconditioning capitalized — with a lower-of-cost-or-market write-down at year-end, documented with wholesale values.
• Floor plan interest is fully deductible outside the business interest limitation — but in a year the dealer actually needs that exception, it can't take bonus depreciation; small dealers under the gross receipts threshold keep both.
• Cash over US$10,000 — including cashier's checks and money orders of US$10,000 or less in a vehicle sale — requires Form 8300 within fifteen days, with related payments aggregated and structuring reportable.
• Buy-here-pay-here dealers can't use the installment method — the gross profit is income at sale; repossessions and charge-offs are specific bad debt deductions (no reserve).
• Dealer reserves are income when received (less chargebacks); service contract and GAP commissions are income, the remitted portions are not.
• Not a specified service trade; the Used Car Rule, the Safeguards Rule, and the dealer license are mandatory and deductible.

The used car dealer's deduction file

Inventory ledger by VIN: cost, fees, transport, reconditioning; year-end lower-of-cost-or-market valuation with wholesale support. Floor plan: interest, curtailments; the floor plan exception's annual bonus test. Deals: cash (Form 8300 log and buyer statements); financed (reserve, chargebacks); BHPH (notes, payments, interest, repossessions at fair market value, specific charge-offs). Add-ons: commissions vs remittances; dealer-obligor service contracts' deferral. Sales tax by deal; trade-in credit. License, bond, Used Car Rule, Safeguards Rule, TILA, BHPH license. Payroll: sales, F&I, reconditioning, collections. The Form 8300 log and the BHPH gross-profit recognition are the two items the IRS examines dealers for.

Worked example

A used car lot with a buy-here-pay-here line sells 410 vehicles: 140 cash deals (US$1.3 million), 150 lender-financed (US$2.1 million, US$62,000 of dealer reserves, US$4,000 charged back on early payoffs), and 120 BHPH (US$1.5 million of sales on the dealer's own notes). Inventory: each vehicle at auction cost plus buyer's fees, transport, and US$1,800 average reconditioning (capitalized); the 64 vehicles on the lot at year-end valued at the lower of cost or wholesale market — US$38,000 of write-downs on aged units documented with auction values. Floor plan: US$96,000 of interest — the dealer is under the gross receipts threshold, so the business interest limitation doesn't apply and bonus depreciation on the new reconditioning bay's lift and equipment remains available. Form 8300: 23 cash receipts over US$10,000 (including four paid with multiple cashier's checks) — filed within fifteen days, buyer statements mailed in January. BHPH: the gross profit on all 120 sales (about US$510,000) is income in the year of sale — not as the notes are collected; the notes' interest income as received; 31 repossessions — each vehicle back into inventory at its fair market value, and the note balances less those values (US$140,000) deducted as specific bad debts; no deduction for the reserve the dealer's financial statements carry. Service contracts: US$210,000 sold, US$150,000 remitted to the administrator (not income), US$60,000 of commissions kept (income); GAP commissions the same. Sales tax: collected on each deal after the trade-in credit, remitted with the titles. Net profit lands in the low six figures — an S corporation (the entity guide), the QBI deduction in full. The lot down the highway reported its BHPH sales on the installment method and missed seventeen Forms 8300 — an examination that recomputed four years of gross profit and assessed the information-return penalties separately.

Official sources

The IRS states: “The amount of cash a customer uses for a transaction and when the customer makes the transaction are the determining factors for when the business must file the Form 8300. Generally, a business must file Form 8300 within 15 days after they receive the cash.” — Internal Revenue Service, IRS Form 8300 reference guide, https://www.irs.gov/businesses/small-businesses-self-employed/irs-form-8300-reference-guide

Publication 538 states: “Under the lower of cost or market method, compare the market value of each item on hand on the inventory date with its cost and use the lower of the two as its inventory value.” — Internal Revenue Service, Publication 538, Accounting Periods and Methods, https://www.irs.gov/publications/p538

Practitioner note

A used car dealer's return follows the vehicle from the auction to the note, and the two items examiners check first are the ones dealers most often miss: the Form 8300 on every cash deal over US$10,000 — cashier's checks included — and the rule that a buy-here-pay-here dealer can't report its sales on the installment method, so the gross profit is taxable the day the car leaves the lot. Our dealer files capitalize reconditioning into each vehicle, write the aged units down to documented wholesale value at year-end, deduct repossession shortfalls as specific bad debts rather than a reserve, and weigh the floor plan interest exception against bonus depreciation when the dealer outgrows the small-business exemption.

See also: For related guidance, see the auto repair shop entity guide; and browse every small business tax guide, by situation.

Next step

Fairlight Accounting is a cross-border accounting and tax practice with a U.S. Tax Desk and a Canadian Tax Desk. Our U.S. Tax Desk handles used car dealer returns — VIN-level inventory with reconditioning capitalization and lower-of-cost-or-market valuation, floor plan interest and the business interest limitation, Form 8300 compliance, dealer reserve and add-on commission treatment, buy-here-pay-here gross profit recognition and repossession accounting, and vehicle sales tax. See pricing or book a call.