<prompt> Human: I earn a small portion of income online by publishing video reviews of products.If I buy a product and publish a review, can I write off the product cost as a business expense even if I continue using it personally? Example: I buy a smartphone and review it, but afterwards I use it as my personal phone.  <response>: You can certainly make that claim as being a necessary business expense. The question is whether the IRS would buy it if you were audited, which probably wont happen.Whether they would agree or not would depend on a lot of things, including the cost of the product, the nature of the review, and how you ultimately use the product. Your safest course of action would be to deduct only a portion of the cost of items that you used outside of your business. 