What is the difference between Due Care and Due Diligence in auditing?

In IESBA Code of Ethics for Professional accountants, one of the fundamental principles is the principle of Professional competence and due care.

Practitioner (auditor) is required to conduct assurance engagement with due care which ultimately requires auditor to act diligently.

Due care simply refers to the degree of care which is expected from a reasonable person under the circumstances. Auditor is neither required nor expected to take special care to conduct an audit engagement. Due care implies the efforts which are ordinarily applied by an ordinary reasonable person i.e. the efforts which are expected from a prudent person in a given situation. Auditor is not expected to act no more than a prudent person with the same set of skills and experience.

Due diligence is one of the requirements that arise out of due care principle. Diligence encompasses the responsibility to act in accordance with the requirements of an assignment, carefully, thoroughly and on a timely basis. The requirements of assignment depends on the nature of assignment itself and also to some extent on the circumstances. In simple words diligence is adherence to the applicable legal and other requirements.

Due care is much wider in scope then due diligence and due care encompass due diligence in itself as one of the key areas.