Depreciation Function is an accounting method used to allocate the cost of physical assets, such as office buildings, vehicles and machinery, over the period in which they are utilized. Depreciation function requires entities to recognize an expense based on the amount of asset use during a given accounting period and helps companies to spread out the expenses associated with their long-term investments. By using depreciation function, businesses are able to track the value of their physical assets over time and plan accordingly for future purchases.