Introduction
Few S corporation deductions cause as much confusion as vehicles. Is the truck a corporate asset or the owner's? Does the shareholder get reimbursed, or does the company simply pay the bills?
Form 1120-S has no dedicated car-and-truck line, so where those costs land is easy to get wrong.
This guide covers U.S. federal reporting for tax year 2026. It walks through deductible costs, Form 1120-S reporting, mileage methods, documentation, and the flow to Schedule K-1 and Form 1040.
An S corporation must be a domestic U.S. entity and cannot have nonresident alien shareholders. Australian residents may also have separate Australian worldwide-income obligations. This article covers U.S. federal reporting only and does not cover Australian tax.
Key Takeaways
- Only the ordinary and necessary business-use share of vehicle costs is deductible; commuting and personal use are not.
- Company-owned vehicles and personally owned vehicles follow different rules.
- The 2026 mileage rate changes mid-year: 72.5 cents, then 76 cents per mile.
- Vehicle costs usually sit in "Other deductions" with a supporting statement.
- Contemporaneous logs and an accountable plan protect the deduction.
What Car and Truck Expenses Can an S Corp Deduct?
Business-use requirement
The test is the one in IRC section 162(a): expenses must be ordinary and necessary in carrying on the business. For vehicles, that means documented trips such as client visits, deliveries, job sites, supplier runs and business errands.
Commuting is excluded. Driving from home to a regular workplace is personal, and so is parking at that workplace. Travel between two work locations on the same day can qualify.
A practical example: an employee-shareholder drives from home to the office (personal), then to a client site and back to the office (business), then home (personal). Only the middle legs count.
Common eligible vehicle costs
IRS Publication 463 lists the actual-expense categories:
- Fuel and oil
- Repairs and maintenance
- Tyres
- Insurance
- Registration fees and licences
- Lease payments
- Garage rent
- Parking and tolls
- Depreciation
Charging costs for electric vehicles are not separately itemised in that list. The standard mileage rates do expressly cover electric and hybrid vehicles, so confirm treatment of charging costs with your adviser if you use actual expenses.
The deductible amount depends on ownership, business-use percentage, the method chosen, and whether the cost is operating or capital.
Capital costs and special deductions
Buying a vehicle is generally a capital expense, not an immediate operating deduction. The purchase price, sales tax and major improvements are recovered through depreciation, Section 179 or bonus depreciation.
For 2026, the key figures are:
- Section 179: maximum deduction of $2,560,000, with a $32,000 cap on specified heavy SUVs. Business-income limits apply, at both corporate and shareholder level.
- Bonus depreciation: 100% for qualifying property acquired and placed in service after 19 January 2025. Binding-contract dates can affect eligibility.
- Passenger-auto limits (vehicles of 6,000 pounds or less, placed in service in 2026):
| Recovery year | With bonus | Without bonus |
|---|---|---|
| First | $20,300 | $12,300 |
| Second | $19,800 | $19,800 |
| Third | $11,900 | $11,900 |
| Each later year | $7,160 | $7,160 |
These caps are reduced by the business-use percentage. Cars are also listed property: business use must exceed 50% to claim Section 179, bonus or accelerated depreciation. If use later drops to 50% or less, excess depreciation is recaptured.
Heavier vehicles (over 6,000 pounds) fall outside the passenger-auto caps but can remain listed property. Weight alone does not guarantee a deduction.
How to Report Car and Truck Expenses on Form 1120-S
Start with the accounting records
Begin with the general ledger and profit-and-loss statement. Separate vehicle costs by vehicle, ownership, business purpose and business-use percentage.
Then reconcile each category to source documents:
- Fuel, repairs, insurance and lease payments to invoices and statements
- Parking and tolls to receipts and card records
- Reimbursements to expense reports
- Business miles to the mileage log
Form 1120-S deduction lines and supporting statements
Form 1120-S has no car-and-truck line. On the final 2025 form, Line 20, Other deductions, requires an attached statement listing each deduction by type and amount.
The 2026 draft form matches, but it is not for filing. Confirm the line number on the final 2026 form and instructions.
Some vehicle costs have their own lines on the 2025 form:
- Repairs and maintenance: line 9
- Rents (lease payments): line 11
- Taxes and licenses: line 12
- Interest: line 13
- Depreciation not claimed elsewhere: line 14, with Form 4562
Put the remaining costs, such as fuel, insurance, parking and tolls, on the Line 20 statement by category.
Company-owned or company-leased vehicles
The corporation records actual operating costs for vehicles it owns or leases. Depreciation applies to owned vehicles; lease payments apply to leased ones.
Personal use is the trap. Under Publication 15-B, personal use of a company vehicle must be included in the employee's wages or reimbursed by the employee. Taxable fringe benefits generally go on Form W-2.
Two valuation shortcuts exist, with limits:
- The $1.50 per one-way commute rule is unavailable for control employees, which includes owners of 1% or more.
- The cents-per-mile rule generally needs 10,000 miles a year or regular business use, and a first-available 2026 vehicle value of no more than $61,700.
Shareholder-owned vehicles and reimbursements
Do not treat a shareholder's personal car as a corporate asset. Instead, reimburse documented business use under an accountable plan, using either the standard mileage rate or substantiated actual expenses.
Record reimbursements as business expense in the books, not as shareholder distributions. If the plan fails the accountable-plan tests (covered below), the payments become wages.
Form 4562, Schedule K and Schedule K-1
Form 4562 is required for depreciation on newly placed-in-service property and any Section 179 deduction (including carryovers). It is also required for depreciation on any vehicle or other listed property, regardless of when the asset was placed in service.
Section 179 is not deducted when calculating ordinary business income. It is separately stated on Schedule K, line 11 and Schedule K-1, box 11.
Other deductible vehicle costs reduce ordinary business income (line 22), which flows to Schedule K, line 1, and then to each shareholder's K-1. The vehicle expense does not become a separate personal deduction. Shareholders report K-1 amounts on Form 1040, subject to basis, at-risk and passive-activity limits.
Standard Mileage vs. Actual Expense: Which Method Fits an S Corp?
Standard mileage method
Multiply qualifying business miles by the IRS rate. The 2026 business rate is split across the year:
| Period | Rate per mile |
|---|---|
| 1 January to 30 June 2026 | 72.5 cents |
| 1 July to 31 December 2026 | 76 cents |
The July rate does not replace the first-half rate retroactively. The rate covers fixed and variable costs, so you cannot add actual operating costs on top. Business parking and tolls can be claimed separately.
Restrictions apply:
- Elect it in the first year an owned car is used for business
- Blocked after certain accelerated depreciation, Section 179 or bonus claims
- Unavailable when five or more vehicles are used simultaneously
Actual expense method
Total the substantiated operating costs, then multiply by the documented business-use percentage. Include depreciation or lease costs. The method needs detailed records and interacts with listed-property rules, Form 4562 and the 50% business-use threshold.
Choosing between the methods
| Factor | Standard mileage | Actual expense |
|---|---|---|
| Recordkeeping | Mileage log plus parking and tolls | Mileage log plus every receipt |
| Predictability | High | Varies with repairs and fuel |
| Best suited to | Lower-cost, high-mileage vehicles | Higher-cost vehicles with large depreciation |
| Depreciation | Built into the rate | Claimed separately |
Run both calculations before you lock in a method for the year.
Hypothetical example (not a recommendation): a shareholder-employee drives 6,000 business miles in the first half of 2026 and 4,000 in the second half.
Reimbursement would be 6,000 × $0.725 = $4,350, plus 4,000 × $0.76 = $3,040, for a total of $7,390. Actual costs for the same vehicle might be higher or lower depending on its price and business-use percentage.
Changing methods and handling multiple vehicles
Switching from standard mileage to actual expenses is generally allowed for owned cars, but depreciation after the switch must use straight-line over remaining useful life, not MACRS. A leased vehicle's mileage choice must continue for the whole lease.
Keep a separate log and expense file for each vehicle. A single combined total for all cars and trucks will not survive scrutiny.
Records, Accountable Plans, and Common Compliance Mistakes
IRC section 274(d) requires adequate records or sufficient corroborating evidence of amount, time, place and business purpose. Choosing the standard mileage rate does not remove that requirement. A weekly log is considered timely.
A good mileage log captures:
- Date
- Starting point and destination
- Business purpose
- Business miles
- Odometer readings or total annual miles
- Vehicle identification
- Personal and commuting miles
For reimbursements, an accountable plan under Treasury Regulation 1.62-2 needs three things: a business connection, substantiation, and return of excess payments. The safe harbours are substantiation within 60 days and returning excess within 120 days.
Failing these tests makes the payments wages, subject to withholding and employment taxes.
Common mistakes include:
- Deducting commuting miles
- Mixing personal and business fuel
- Claiming standard mileage and the same actual costs
- Reconstructing mileage after year-end
- Depreciating a personally owned vehicle as a corporate asset
- Failing to report personal use of a company vehicle
The cost of poor records is real. In Garza v. Commissioner (T.C. Memo. 2014-121), the court disallowed a $20,085.50 vehicle deduction because the taxpayer's planner did not establish the amount, time or business purpose of each trip. That was an employee case, but the substantiation lesson applies to S corporations.
2026 Filing Workflow and Checklist for S Corp Owners
Pre-filing checklist
Gather these before preparing the return:
- Vehicle titles or lease agreements
- Purchase documents
- Fuel and repair receipts
- Insurance and registration records
- Parking and toll receipts
- Mileage logs for each vehicle
- Reimbursement reports
- Prior depreciation schedules
- Personal-use calculations
Workflow in order
- Determine ownership of each vehicle.
- Identify business use and calculate the business-use percentage.
- Choose the permitted method for each vehicle.
- Record the expense or reimburse it under the accountable plan.
- Verify the Line 20 reference on the final 2026 Form 1120-S.
- Prepare the attached statement and any Form 4562.
- Reconcile Schedule K and each Schedule K-1.
- Review the shareholder's Form 1040 treatment, including basis and loss limits.
A calendar-year 2026 return is due 15 March 2027. Form 7004 gives an automatic six-month filing extension to 15 September 2027, but it does not extend the time to pay any tax.
Getting help
VJM Global provides accounting, tax compliance and U.S.-compliant professional support for Australian businesses with U.S. obligations. Its team includes CPAs and U.S.-compliant professionals.
If you need help with bookkeeping or S corporation compliance documents, enquire through [email protected]. Australian tax advice is not part of that U.S. compliance support.
Frequently Asked Questions
How do you report car and truck expenses on Form 1120-S?
It depends on ownership and method. Costs generally fall into the corporation's deduction lines or the Line 20 "Other deductions" statement. Support them with Form 4562 where required, reimbursement records and mileage logs.
What expenses can an S Corp deduct on Form 1120-S?
The documented business-use share of ordinary and necessary vehicle costs. Operating expenses, depreciation, Section 179 and lease costs are treated differently. Personal and commuting costs are not deductible.
Where does S Corp income go on Form 1040?
Shareholders receive their share of business income and separately stated items on Schedule K-1. Box 1 income generally goes to Schedule E. Wages are reported separately on Form W-2.
Can an S Corp reimburse a shareholder for a personally owned vehicle?
Yes, under an accountable plan. Reimbursement can use the standard mileage rate or substantiated actual expenses. Timely mileage and expense substantiation is required.
What records are needed to claim vehicle expenses for 2026?
Keep mileage logs showing business purpose, receipts, and ownership or lease documents. Add repair and fuel records, reimbursement reports and depreciation documentation where relevant.
