Amortization expense on an income statement is a non-cash expense used to reduce the value of intangible assets over time. This can include expenses such as trademark or patent costs, research and development costs, and more. Over time, these expenses are charged to the income statement as they decline in value. By amortizing them, companies can reflect the correct financial condition of their business to investors in an accurate manner. Amortization is an important tool for businesses to use when attempting to accurately gauge the true earnings potential of a company over time.