Internal audits and auditor competence

Answer:
To keep your certification, you will be audited annually by the certification body, what is called a surveillance audit. To avoid a major nonconformity at that audit your organization should perform an internal audit to the environmental management system at least annually.

2. Must it be by someone who is certified or just knowledgeable?

Answer:
Your internal auditor should be someone considered competent according to your organization’s own requirements. It is your organization that establishes the required competence needed for an internal auditor.

The following material will provide you with information about internal audits:
- ISO 14001 – Internal Audits in the EMS: Five Main Steps - https://advisera.com/14001academy/blog/2019/08/27/key-iso-14001-benefits-to-customers/nowledgebase/internal-audits-in-the-ems-five-main-steps/
- Creating an ISO 14001 internal audit plan - https://advisera.com/14001academy/blog/2017/01/16/creating-an-iso-14001-internal-audit-plan/
- free online training ISO 14001:2015 Internal Auditor Course
https://advisera.com/training/iso-14001-internal-auditor-course/
- book - The ISO 14001:2015 Companion - https://advisera.com/books/the-iso-14001-2015-companion/