There are many good reasons to keep detailed expense reports. First and foremost: It’s the law. Under the Income Tax Act, you are required to keep all documents that are pertinent for establishing your tax obligations for six years after the end of the tax year to which they relate.
Beyond the legal obligation to do so, keeping detailed expense reports will allow you to track your business expenditures, know where your money is going and adjust your strategy to maximize the impact of every dollar you spend. You may also come to realize that you are forgetting to claim deductions (and goods and services tax/harmonized sales tax refunds) for business-related expenses.
Accounting software such as QuickBooks comes with built-in expense tracking features that make it easy to prepare expense reports.