Outsourced Internal Audit Cost vs In-House Internal Auditors

What makes up the cost of an internal audit programme?

Audit days, whoever the auditor is, plus whatever it takes for those days to produce reliable findings. With in-house auditors, those costs are spread out: hours, training, competence maintenance. With an external auditor, they are invoiced. The comparison only makes sense item by item.

The auditees’ time is the same in both models: an audit that involves neither the process owners nor the operators audits nothing.

What makes audit volume vary?

Your standards first, then your sites, your risks and your calendar. Volume is calculated from the programme, not from a flat fee.

Food safety schemes set a floor. BRCGS Food Safety Issue 9 requires at least four audit dates spread throughout the year and every activity covered each year (3.4.1). IFS Food Version 8 requires every one of its requirements to be audited within a 12-month programme, carried out within 15 months at most (5.1.1, KO No. 8). For a group certified to FSSC 22000 Version 7 on a multi-site basis, the management system, the central function and every site are audited at least once a year (2.5.18.2). ISO standards leave frequency to the company, based on the importance of the processes, changes and past results.

A combined audit reduces repetition: one opening meeting, one floor walk, interviews common to the standards. ISO 19011:2026 recognises the principle. The saving depends on how integrated your system really is, as our analysis of the cost of a combined QHSE certification audit shows.

Which hidden costs weigh on in-house auditors?

Those that appear on no invoice, but that the company’s budget pays all the same:

• Initial training. An internal auditor course per person, plus training in the GFSI scheme. For a multi-site FSSC 22000 group, the scheme requires a 40-hour course for the internal Lead Auditor, 16 hours for the other auditors and 8 hours of scheme training for all, with two years’ food industry experience including one year in the organisation.
• Competence maintenance. An upgrade at each change of version, as with ISO 9001:2026 and ISO 14001:2026, and calibration between auditors; multi-site FSSC 22000 requires annual performance monitoring of internal auditors.
• Time taken away from the job. A production manager who audits is not producing; in high season, it is often the audit that gets sacrificed.
• A trained auditor leaving. The competence leaves with them, and the schedule slips.
• Lack of independence. BRCGS forbids an internal auditor from auditing their own work (3.4.2), and IFS requires auditors independent from the audited department (5.1.2). In a small organisation, the quality manager cannot audit the management of the system they run.
• The audit that finds nothing. The most expensive of all: a gap not detected internally comes out at the certification audit, with an action plan against a deadline.

The cost of training internal auditors is detailed in our article on the cost of ISO 9001 internal auditor training. In Morocco, when that training is part of the training plan, it may qualify for the special training contracts (contrats spéciaux de formation, CSF) of OFPPT (Office de la formation professionnelle et de la promotion du travail, the national vocational training office), under their rules and with no guaranteed amount. An outsourced audit, on the other hand, is not a training action. The rules and a simulation are on our CSF OFPPT funding page.

In-house, outsourced or mixed: which model costs least?

The one that covers your requirements with independent auditors in the least total time. The table gives a qualitative logic; your programme provides the answer.

The mixed model is the one we recommend most often. The external auditor takes the audits that call for independence (system management, management review, the quality department) or rare expertise (IFS KO requirements, BRCGS fundamental requirements), and trains, in pairs, the internal auditors who carry out the rest. If the whole QHSE function is in question, also compare with our analysis of the cost of an in-house or outsourced QHSE manager.

How do you compare two offers for an outsourced internal audit?

On content, not on the day rate. Two offers at the same price can cover very different services. Check that each offer specifies:

• the number of audits, their scope and their criteria, matched to your programme;
  
• the days of preparation, auditing, reporting and follow-up, separately;
  
• the effectiveness check on actions, not just their closure;
  
• travel and any remote share;
  
• the auditor’s qualification for each standard audited;
  
• their declaration of no conflict of interest and their confidentiality undertaking;
  
• the report format and the tool for sharing results;
  
• the summary for the management review and the annual programme review.
  

Site preparation, which determines how many of the days are actually useful, is described in our how-to on preparing for an outsourced internal audit; the rules of each standard, in our guide to outsourced internal audits.