The paper analyzes some concepts in the field of Financial and Management Accounting that are well known by economists. The concept of contribution margin adds new notions in the computation of the break-even point. The relevant range of the data is important to avoid absurd prospections. The fallacy of the analysis of total costs, where the fixed costs, as they are allocated show difterent total costs, is also indicated. Finnaly, it is shwon a chart where the relevance of the contribution margin can be seen.
Contribution margin; contribution margin ratio; relevant range; total cost; variable cost; fixed cost breakeven point