The procedures known as "1st party audits" will generally be carried out by an "internal auditor", i.e. usually, but not necessarily, by a company employee who has been trained for this purpose. In this case, only one party, namely the company itself, is involved. Nevertheless, internal audits can also be carried out by external auditors, but only on condition that they are qualified auditors.
Auditors of a certification company are not allowed to perform internal audits at companies if they themselves perform the certification audit for that company.

None

None

None