Traditional and contribution margin income statements provide a detailed picture of a company's finances for a given period of time. While both serve the purpose of showing whether a company has a net profit or loss, they differ in the way they arrive at that figure.

Traditional income statement
Also known as a profit and loss statement, a traditional income statement shows the extent to which a company is profitable or not during a given accounting period. It provides a summary of how the company generates revenues and incurs expenses through both operating and non-operating activities.

Contribution margin income statement
In a contribution margin income statement, a company's variable expenses are deducted from sales to arrive at a contribution margin. A contribution margin is essentially a company's revenues minus its variable expenses, and it shows how much of a company's revenues are contributing to its fixed costs and net income. Once a contribution margin is determined, a company can subtract all applicable fixed costs to arrive at a net profit or loss for the accounting period in question.

While a traditional income statement works by separating product costs (those incurred in the process of manufacturing a product) from period costs (those incurred in the process of selling products, as opposed to making them), the contribution margin income statement separates variable costs from fixed costs. In a contribution margin income statement, variable selling and administrative periods costs are grouped with variable product costs to arrive at the contribution margin.

A traditional income statement uses absorption or full costing, where both variable and fixed manufacturing costs are included when calculating the cost of goods sold. The contribution margin income statement, by contrast, uses variable costing, which means fixed manufacturing costs are assigned to overhead costs and therefore not included in product costs.

Companies are generally required to present traditional income statements for external reporting purposes. Contribution margin income statements, by contrast, are often presented to managers and stakeholders to analyze the performance of individual products or product categories. Companies can benefit from contribution margin income statements because they can provide more detail as to the costs and resources needed to produce a given product or unit of a product. While both income statements ultimately serve the purpose of showing whether a company is profitable or not over a certain period of time, the contribution margin income statement can offer additional insight as how to that net profit or loss came to be. 

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