Publication 535, Chapter 4 wrote:Interest You Can Deduct
You can generally deduct as a business expense all interest you pay or accrue during the tax year on debts related to your trade or business. Interest relates to your trade or business if you use the proceeds of the loan for a trade or business expense. It does not matter what type of property secures the loan. You can deduct interest on a debt only if you meet all the following requirements.
You are legally liable for that debt.
Both you and the lender intend that the debt be repaid.
You and the lender have a true debtor-creditor relationship
Interest You Cannot Deduct
Certain interest payments cannot be deducted. In addition, certain other expenses that may seem to be interest are not, and you cannot deduct them as interest.
You cannot currently deduct interest that must be capitalized, and you generally cannot deduct personal interest.