Limits. The amount you can claim for section 179 and depreciation deductions may be limited. Maximum limits apply depending on the year in which you placed your car in service. You have to adjust the limits if you did not use the car exclusively for business. See Depreciation Limits, later.

Unadjusted basis. You use your unadjusted basis to figure your depreciation using the MACRS depreciation chart explained later under Modified Accelerated Cost Recovery System (MACRS). Your unadjusted basis for figuring depreciation is your original basis increased or decreased by certain amounts.

To figure your unadjusted basis, begin with your original basis in your car, which generally is its cost. Cost includes sales and luxury taxes, destination charges, and dealer preparation. Increase your basis by any substantial improvements you make to your car, such as adding air conditioning or a new engine. Decrease your basis by any deductible casualty loss, section 179 deduction, diesel fuel tax credit, gas guzzler tax, clean-fuel vehicle deduction, and qualified electric vehicle credit. See Publication 535 for more information on the clean-fuel vehicle deduction, and the qualified electric vehicle credit.

If your business use later falls to 50% or less, you may have to include in your income any excess depreciation. See Car Used 50% or Less for Business, later, for more information.

If you acquired the car by gift or inheritance, see Publication 551, Basis of Assets, for information on your basis in the car.

Improvements. A major improvement to a car is treated as a new item of 5-year recovery property. It is treated as placed in service in the year the improvement is made. It does not matter how old the car is when the improvement is added. Follow the same steps for depreciating the improvement as you would for depreciating the original cost of the car. However, you must treat the improvement and the car as a whole when applying the limits on the depreciation deductions. Your car's depreciation deduction for the year (plus the depreciation on any improvements) cannot be more than the depreciation limit that applies for that year. See Depreciation Limits, later.

Effect of trade-in on basis. When you trade an old car for a new one, your original basis in the new car is generally your adjusted basis in the old car plus any additional payment you make.

Traded car used only for business. If you trade in a car that you used only in your business for another car that will be used only in your business, your original basis in the new car is your adjusted basis in the old car, plus any additional amount you pay for the new car.

Example 1. Paul trades in a car that has an adjusted basis of $3,000 for a new car. In addition, he pays cash of $7,000 for the new car. His original basis of the new car is $10,000 (his $3,000 adjusted basis in the old car plus the $7,000 cash paid). Paul's unadjusted basis would be the same unless he claims the section 179 deduction or has other increases or decreases to his original basis.

Click "Next" below for more information on this topic.

The Vehicle Mileage & Maintenance Record Book is designed for busy professionals like you who are tired of cheap tax information recording tools that fall apart and don't provide adequate room on forms for writing. Order one of our auto mileage logs today and start making this essential task simple and quick. Each book comes with a MONEY BACK GUARANTEE!  Click here to order by using our online shopping cart, downloadable order form, or through Amazon.com.