The business case for an information system investment should be available for review until the:

The business case for an information system investment is a document that provides the rationale and justification for the investment, based on the expected costs, benefits, risks, and impacts of the project12. The business case should be available for review until the benefits have been fully realized, because it serves as a baseline for measuring the actual performance and outcomes of the project against the planned ones34. This helps to evaluate the success and value of the investment, and to identify any gaps or issues that need to be addressed5.

References

1: The Business Case for Security - CISA

2: Beyond the Business Case: New Approaches to IT Investment

3: #HowTo: Build a Business Case for Cybersecurity Investment

4: ISACA CISA Certified Information Systems Auditor Exam … - PUPUWEB

5: The Business Case for Security | CISA