The biggest mistake in assessing an internal candidate for an executive role is judging them on the job they already do.
They may be excellent at it. That doesn't automatically tell you whether they can operate at the next level.
Equally, internal candidates are sometimes held to a strange standard. The Board knows every weakness because it has seen them up close, while an external candidate arrives with a polished CV and two hours of interview evidence.
A fair process needs better comparison than that.
Define the future role first
Be explicit about the outcomes, scale, relationships and judgement the new role requires.
What will be different from the candidate's current job? Which decisions become theirs? What level of ambiguity will they face? Who will they need to influence? What will they have to stop doing themselves?
This gives you something meaningful to assess against.
Look for evidence of operating at the next level
Past performance matters, but look for examples where the person has already stretched beyond their formal remit.
Have they led across functions? Influenced the Board? Managed competing stakeholders? Built capability through others? Made difficult calls with incomplete information? Operated through significant change?
The quality of the evidence matters more than a competency score.
Use more than an interview
For a material executive appointment, I would normally combine structured interviews with other evidence.
That might include psychometrics, a business or case discussion, stakeholder feedback, 360 data and references to previous performance. The exact mix should fit the role rather than becoming an assessment-centre obstacle course.
Compare with the external market
This is the part that makes the process much stronger.
Identify what credible external alternatives look like. Compare experience, scale, capability and remuneration. If appropriate, speak to the market.
The question becomes: is this internal person the best realistic option, not simply the best person we already know?
Assess development risk, not just readiness
“Ready now” can be a lazy label.
Very few people are perfectly ready for a bigger executive role. The more useful question is whether the gaps are developable and whether the organisation can support them.
A candidate might lack one piece of experience but have exceptional organisational knowledge, trust and leadership credibility. Another may tick every technical box but require a much bigger cultural adjustment.
Both are risks. Compare them properly.
Give the Board an independent view
Where the decision is sensitive, independent assessment helps everyone.
It gives the Board evidence. It gives the internal candidate a credible process. And it reduces the risk of a decision being seen as predetermined.
Internal succession should be a competitive advantage. It only becomes one if organisations are prepared to assess it with the same rigour they would apply to an external appointment.