What cost is incurred if a bug in the requirements is not detected until code implementation?

The cost incurred if a bug in the requirements is not detected until code implementation primarily relates to test case development time. When a requirement is found to have a bug after the code has been implemented, it often necessitates the creation of new test cases or revisions to existing ones to ensure that the bug is effectively identified and validated through testing. This process can involve significant time and effort, as the existing test cases may need to be revised or even new ones created from scratch based on the updated understanding of the requirements.

Moreover, the later in the software development life cycle a defect is found, the more time-consuming and costly it becomes to address it, since it often involves reworking not just the code but also all associated documentation, testing, and potentially even impacts on project timelines. Thus, the requirement phase is the most cost-effective time to catch bugs, and failure to do so leads directly to increased effort in the testing phase, evidenced by the additional time required for test case development.