If you use your home office regularly and exclusively as your principal place of business, including everything from simple administration to management, you can qualify to deduct home office expenses. Even an electrician who uses their home office to order supplies and make appointments, even though she performs a majority of the business outside her home office, can take the deduction. One catch - you cannot use the space at all for any personal reason and still qualify. If your child uses your computer for video games, you can no longer claim the home-office deduction. The office does not need to be a separate room; it can be part of a dining room, basement, or even a bedroom, as long as that part of the house is used for no other purpose. If you work out of your house, you can deduct a portion of home expenses, such as rent, mortgage interest, insurance, security systems, utilities, casualty losses and depreciation, as well as maintenance and repairs that are normally personal expenses. Bringing work home for your convenience doesn't qualify you for the deduction, but bringing work home because your employer does not provide you a place to perform your duties does. Don't forget to deduct the smaller items often overlooked: the cost of business cards and paper fliers, copy shop expenses for copies or computer time, annual fees and interest expenses on credit cards used exclusively for business, and the cost of postage, overnight deliveries, and courier services. You can also claim 55 cents per mile for business use of your personal vehicle.