When loan costs are significant, they must be amortized because of the matching principle. In other words, all of the costs of a loan must be matched to the accounting periods when the loan is outstanding.
To clarify this, let's assume that a company incurs legal, accounting, and registration fees of $120,000 during February in order to obtain a $4 million loan at an annual interest rate of 9%. The loan will begin on March 1 and the entire $4 million of principal will be due five years later. The company's cost of the borrowed money will be $360,000 ($4 million X 9%) of interest each year for five years plus the one-time loan costs of $120,000.
It would be misleading to report the entire $120,000 of loan costs as an expense of one month. Hence, the matching principle requires that each month during the life of the loan the company should report $2,000 ($120,000 divided by 60 months) of interest expense for the loan costs in addition to the interest expense of $30,000 per month ($4 million X 9% per year = $360,000 per year divided by 12 months per year). The combination of the amortization of the loan cost plus the interest expense will mean a total monthly interest expense of $32,000 for 60 months beginning on March 1.