The GAAP standards cover financial reporting as a whole. 

For example, GAAP stipulates how to file income statements, what financial periods to include, and how to report cash flow. 

GAAP guidelines require businesses to prepare financial statements according to the matching principle using the accrual basis of accounting.Because the objective is to ensure that expenses match with revenues, expenses are reported in the period in which the expense is incurred regardless of when the expense is paid.