IRS Link to Publication — Found Here
Publication 463 discusses common business-related deductions such as travel, entertainment, gift, and vehicle expenses.
The guide is meant to explain which expenses are deductible, how to report them, how to prove them, and what to do if you get reimbursed. Business expenses are commonly paid for out-of-pocket by employees and business owners, and many of them are unsure exactly which expenses are tax-deductible.
Publication 463 explains commonly-used deductions, how to file them, what records are needed to prove them, and how to handle some of the paperwork when things change, such as getting reimbursed or partially reimbursed. Individuals will normally be able to deduct unreimbursed business expenses on their individual tax return (Form 1040, et al).
Publication 463 can be used as a reference for individuals and businesses. The most common deductions of this type are for travel, cars, and meals. Some are capped at 50% of the expenses, but some individuals or situations are not subject to the cap.