Managers and management accountants should distinguish fixed from variable costs and then evaluate how the level of fixed costs and variable costs they choose will affect the risk-return tradeoffs of their firms. As we have explained, distinguishing fixed from variable costs is fairly straightforward in some cases. In others it’s more challenging because costs do not vary only with the number of units sold but with the number of different types of products or services offered, the number of batches in which products are produced, or the complexity of operations. Chapter 10 describes techniques managers can use to separate fixed costs from variable costs. Regardless, differentiating fixed from variable costs requires careful judgment.