CCA is essentially a yearly deduction allowed by Revenue Canada (CRA) to expense a portion of an asset. For example if you a purchase a computer you are not allowed to expense it all in one year since the computer will likely last at least 3 years or longer. A useful life is assigned to an asset and an annual rate at which they should be expensed is applied. An accelerated CCA allows the company to shorten the number of years of an assets useful life, enabling them to claim the capital cost in a shorter period of time.