Management systems such as ISO 9001, ISO 14001 and OHSAS 18001, require internal audits are scheduled at planned intervals; they do not established a specific frequency nor do they establish that all processes need to have a yearly internal audit. Therefore, organizations need to establish a frequency which is right for their business. Audits can be performed monthly, quarterly, twice a year or once a year. There are some criteria which should be considered before defining a frequency.

Complexity of the Processes

  • Crucial or high risk processes should be audited on a more frequent basis, perhaps quarterly or twice a year
  • Low risk processes can be audited just once a year or every other year

Maturity of the Processes

  • Well established processes that run efficiently can be audited once a year or every other year
  • New developed processes should be audited quarterly until they are stable

Past Experience

  • Processes that have a history of frequent deficiencies or non-conformities, can be audited quarterly or twice a year
  • Processes with troubles achieving targets and objectives can also be audited quarterly or twice a year

There are other factors that can influence the frequency of auditing, such as:

  • An organization’s budget for the execution of internal audits
  • Regulatory or customers’ requirements

There is no need to audit every process all at once, it is more suitable to spread out the internal audits throughout the year auditing different processes at different times. Auditing many processes all at once can be exhausting and process deficiencies or areas for improvements may be overseen.


Although most standards do not require that all process be audited every year, it is a common practice in many organizations. There are even some organizations, with mature and well-establish management systems, which schedule their audits over a three year time plan. Every organization needs to take a close look at each of their processes, their management systems and other applicable requirements in order to establish a rational schedule which fits their needs and is right for them.


  1. Our last Recertification Audit for ISO9001-2008, the auditor insisted IA’s need to cover the standard within 1 calendar year. This does not seem to be the case! Do I have an opportunity to challenge this interpretation?

    • Hi Jim,

      You are correct, there is no requirement in the ISO 9001:2008 standard that makes it mandatory to audit all clauses of the standard in any specific amount of time. It only indicates that you must “conduct internal audits at planned intervals” and this shall consider “the importance of the processes and areas to be audited, as well as the results of previous audits”. If you can demonstrate that you have planned the frequency you audit each process, taking these things into consideration you have met the requirements. You definitely should challenge this interpretation. Hopefully this was helpful!

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