What is one of the three conditions under which an auditor may provide non-audit services without impairing independence?

One of the three conditions that allow an auditor to provide non-audit services without jeopardizing their independence is when the engagements are considered non-audit services at the time. This condition is essential as it clarifies that the specific services provided do not relate to the audit objective and, therefore, do not create a conflict of interest that could impair the auditor's objectivity.

In this context, recognizing the nature of the engagement as non-audit helps maintain the auditor’s independence by ensuring that the services provided are separate from those related to the audit. This separation is vital in maintaining the integrity of the audit process and the auditor's impartiality. The focus remains on the audit itself, ensuring that the non-audit services do not compromise the quality or thoroughness of the audit findings.

The other options do not accurately reflect the conditions under which independence can be maintained. For instance, approving services retrospectively does not address the nature of the services being provided at the time, and offering services at no charge does not eliminate the potential for perceived bias. Similarly, generating significant additional revenue does not relate directly to maintaining the auditor's independence—it might even raise concerns about dependency on that revenue stream, which could impair objectivity.