The cost of CompEx varies depending on whether you attend a formal training course before the assessment, which units you are taking, and which assessment centre you use. This guide gives a realistic overview of what to budget for CompEx in 2025.

CompEx Assessment Fees

The formal CompEx assessment fee (covering the written and practical assessment) varies between assessment centres but typically falls in the range of £500–£800 per unit. Many candidates take multiple units simultaneously (e.g. Ex01 and Ex03 together), which can reduce the overall cost.

Training Course Costs

Most candidates attend a formal CompEx preparation course before their assessment. These courses typically run for 5–7 days and are offered by a range of training providers across the UK. Course fees typically range from £1,200–£2,000 per candidate depending on the provider, location, and number of units covered.

Total Cost

Including preparation course and assessment fees, candidates typically budget £1,700–£2,800 for a CompEx Ex01/Ex03 combination. For Ex02/Ex04 additions the cost increases accordingly.

Online Preparation — A Cost-Effective Alternative

Online preparation platforms like EX Academy offer a significantly more cost-effective way to build the knowledge foundation before attending a formal course or assessment. At £19.99/month, you can work through all 15 inspection simulations, 15 equipment selection scenarios, 14 training modules, and 1,185+ practice questions — putting yourself in a much stronger position before your formal assessment course and reducing the risk of a costly resit.

Employer Funding

Many employers in the oil and gas, offshore, and petrochemical sectors fund CompEx assessments for their electricians as part of their ATEX/DSEAR compliance obligations. If your employer requires CompEx, they should be covering the assessment cost — and may also fund preparation courses. Online preparation is often self-funded as a cost-effective supplement.

Costs Candidates Often Overlook

Beyond the headline course and assessment fees, factor in a few costs that catch first-time candidates out:

  • Travel and accommodation — if your nearest assessment centre is a significant distance away, multi-day courses mean several nights' accommodation plus travel, which can add several hundred pounds
  • Time off work — a 5-7 day course represents a full working week; if you're self-employed or contracting, factor in lost earnings alongside the direct course cost
  • Resit fees — if you don't pass first time, resits typically incur the assessment fee again (sometimes at a reduced rate), which is why thorough preparation before the formal course pays for itself
  • Renewal every 5 years — CompEx isn't a one-off cost; budget for the same process repeating at each 5-year renewal point

Self-Funded vs Employer-Sponsored

If you're self-funding because you're between contracts, new to the industry, or your employer doesn't cover training costs, the online preparation route becomes particularly valuable — it lets you build genuine competency before committing to the more expensive residential course, reducing the real risk of a costly resit. Employer-sponsored candidates have less direct cost pressure, but thorough preparation still benefits them: fewer resits mean less time away from billable work, and a confident first-time pass reflects well when employers are deciding who to put forward for future certifications or site responsibilities.

Is It Worth the Investment?

For most electricians working or seeking to work in hazardous areas, CompEx isn't optional in any meaningful sense — without it, access to the majority of oil and gas, petrochemical, and offshore sites simply isn't available. Viewed against the earning potential it unlocks (offshore and specialist hazardous area rates are typically well above standard electrical rates), the few thousand pounds in training and assessment costs is recovered quickly once you're working in the sector.