You can deduct all business travel expenses, including travel from one job site to another; travel to a temporary assignment (generally one year or less) outside your general area of residence; travel between primary and secondary jobs; and all other cab, bus, train, airline, and automobile expenses. Normal commuting expenses to your primary job cannot be deducted. If your home is your principal place of business, you can deduct daily transportation expenses from your home to any work location.

You may deduct expenses for an automobile you own in one of two ways.

Record and deduct your actual expenses, including depreciation
OR
Record your mileage and deduct a standard amount per mile of travel, plus parking and toll fees

The standard mileage rate is 55 cents per business mile in 2009.

If expenses include accelerated depreciation, deducting actual expenses may at first provide a larger deduction. But, keep in mind that you may not switch to the standard mileage rate in later years when it provides the larger deduction. If you lease a vehicle, you can either deduct actual expenses or take the standard mileage deduction. Detailed recordkeeping is important to substantiate your deduction.

If your employer reimburses you for business travel, the reimbursement is not usually included in your income, and you are not permitted to deduct expenses. Travel expenses for which you are not reimbursed are deductible as miscellaneous itemized deductions subject to the 2% of AGI floor.