Where Does Interest Expense Go on a Business Tax Return?

One payment, two destinations

A loan payment leaves the bank as one amount and splits in the books: principal reduces the note on Schedule L, interest is the deduction on page 1. The lender's amortization schedule is the authority for the split.

Both failure modes are visible on a trial balance. Everything posted to interest leaves the loan balance frozen at its original amount while interest expense runs far too high. Everything posted to principal amortizes the loan too fast and loses the deduction.

The check: the ending balance in notes payable should equal the payoff figure on the lender's December statement.

Credit card finance charges are interest

Interest and fees on a business card are interest expense, not purchases. They belong on the interest line rather than mixed into whatever expense account the rest of the statement was coded to.

Not all interest is deductible here

Interest on a corporate federal tax underpayment is generally not deductible.

Investment interest on a pass through return is separately stated on Schedule K, because the limitation applies at the owner level.

Construction period interest may have to be capitalized into the asset rather than deducted.

Interest on a loan whose proceeds went to the owner personally is not a business deduction, however the note is titled. A shareholder loan where the money never reached the business is the usual version.

Section 163(j)

Business interest can be limited to a percentage of adjusted taxable income, with a small business exemption based on average annual gross receipts over the prior three years. Most closely held clients fall under the exemption; those that do not need Form 8990.

It is worth knowing which side of the threshold a client is on before assuming the whole balance is deductible, particularly for a leveraged business whose receipts have been growing.