For example I go to Home Depot to purchase items for my business, but I also purchase items for personal use. I can certainly deduct the items I purchased for the business. Can I also deduct the mileage? If not, can I deduct part of the mileage? How do I allocate the mileage to business vs personal if using the standard mileage deduction?
If you incur an expense (mileage) in the process of meeting both personal and business needs, it is usually not deductible for business purposes. There is a presumption that the expense would have been incurred to meet your personal needs, whether or not there was an additional "business" benefit.
Individual facts and circumstances may, however, make a dual-purpose trip deducible.
In cases such as you described, I would ask "what was the primary reason for your trip to Home Depot - to buy business supplies or meet personal needs?" If I purchased $5000 of building supplies for my home repair business and $50 for personal home project supplies, then the entire trip would have been "business". Conversely, I could not justify a business purpose if I was at Home Depot for personal home project supplies and remembered that I needed a network cable for my home office.
However you decide to allocate these costs (or not), be consistent from trip to trip. For example - divide the mileage equally between business & personal.
If you incur an expense (mileage) in the process of meeting both personal and business needs, it is usually not deductible for business purposes. There is a presumption that the expense would have been incurred to meet your personal needs, whether or not there was an additional "business" benefit.
Individual facts and circumstances may, however, make a dual-purpose trip deducible.
In cases such as you described, I would ask "what was the primary reason for your trip to Home Depot - to buy business supplies or meet personal needs?" If I purchased $5000 of building supplies for my home repair business and $50 for personal home project supplies, then the entire trip would have been "business". Conversely, I could not justify a business purpose if I was at Home Depot for personal home project supplies and remembered that I needed a network cable for my home office.
However you decide to allocate these costs (or not), be consistent from trip to trip. For example - divide the mileage equally between business & personal.
Your Home Depot example is good. Generally, the IRS likes some kind of method for allocating the dual-use cost. In this case, I would suggest to keep records of your mileage and how much you spent at the destination, and then use that to calculate "equivalent mileage". For example, if your round-trip mileage to Home Depot is 20 miles, and if $150 of a total $200 purchase was a business expense, then the mileage to enter into TurboTax would be 20 x 150/200 = 15 miles.