The four different approaches to implementing the matching principle are: (1) Recognizing an expense based on an exact cause-and-effect relationship between a revenue and expense event. Cost of goods sold is an example of an expense recognized by this approach. (2) Recognizing an expense by identifying the expense with the revenues recognized in a specific time period. Office salaries is an example of an expense recognized by this approach (3) Recognizing an expense by a systematic and rational allocation to specific time periods. Depreciation is an example of an expense recognized by this approach. (4) Recognizing expenses in the period incurred, without regard to related revenues. Advertising is an example of an expense recognized by this approach.