Business processes can be assessed by checking transaction documents for inconsistency risks and can be classified into two categories. Inconsistency refers to a mismatch between items (product name, quantity, unit price, amount price, etc.) among transaction documents. For any process in the first category, the consistency of any pair of transaction documents in the process is checked, and there is no risk of inconsistency. For any process in the second category, the consistency of some pairs of transaction documents in the process cannot be checked, and there is a risk of inconsistency. This paper proposes a method and a tool for the assessment of risk inconsistencies. The assessment can be used to design and evaluate business processes for a company’s internal control over financial reporting. A business process diagram and inconsistency risk detection algorithm for classifying business processes is provided. A BPA-tool (Business Process Assessment tool) is also presented.