Knowledge transfer around retirement only works if you start 3 to 5 years before your senior engineers leave. If you wait until someone actually walks out the door, the knowledge is already gone: it lives in heads, not in documentation. Organizations without a plan today will soon be buying expensive interim solutions for problems that were preventable.

You probably have him on your team. That one engineer who understands the legacy system. Who knows why that odd workaround was built in ten years ago. Who you call when things really go wrong, in the middle of the night.

That person is going to retire. Not in twenty years. In a few years.

And you have no idea what happens then to the knowledge he takes with him.

The aging workforce hits IT teams harder than other departments, because senior engineers often spend decades on the same systems. That knowledge was never written down, because there was never time or reason to. Now that group is approaching retirement, all roughly at the same time.

The numbers confirm what you already feel on the floor. The median age in the EU was 44.9 years at the start of 2025, with more than 22% of the population over 65. That's roughly one retiree for every three workers, a ratio that hurts extra in the IT sector because the inflow of young talent lags behind the outflow of seniors.

The European Commission calls the Netherlands a digital frontrunner, but warns that progress is mainly held back by a shortage of ICT specialists, limited adoption among SMEs and fragmentation within government.

The Netherlands has relatively many ICT specialists: 7.2% of the workforce versus an EU average of 5%. Yet the country faces a structural shortage, partly due to aging, part-time work and a lack of technically trained newcomers.

This is not an incident. This is a demographic shift you can't solve with a job posting.

Waiting with knowledge transfer until a senior engineer enters their notice period costs you an average of 12 to 24 months of delay on major IT projects. That's not a rough guess, that's the reality with cloud migrations, ERP replacements and security upgrades that grind to a halt as soon as the only person who truly understands the system is gone.

The problem goes deeper than a staffing gap. Many organizations have core systems that in practice are understood by a handful of people. When that group disappears, the risk of incidents, downtime and what you could call "person lock-in" rises sharply: knowledge that only exists in heads, never in documentation.

Security and compliance suffer too. Departing seniors take knowledge with them about vulnerabilities, temporary fixes and informal agreements (who you call during an incident, which patch hasn't been rolled out yet). Without a handover, an audit becomes harder and an outage more expensive.

You feel it financially as well. In a market with structural shortages in engineering roles, organizations that act too late are forced to drive up salaries, hire expensive interim profiles, or put juniors in senior roles without the guidance that requires. That last one goes wrong sooner or later.

The most effective forms of knowledge transfer revolve around collaboration on concrete tasks, not standalone documentation sessions. Pair a senior engineer with a mid-level colleague on a real project, and the implicit knowledge (why something was built that way, what the pitfalls are) surfaces naturally.

Dual roles are the most practical way to do this. A junior or medior literally works in the shadow of a senior, not as a note-taker but as an active contributor. That works better than a wiki that's outdated again after three months.

Documentation remains necessary, but not as a goal in itself. Write down what a new colleague needs to act independently during an incident. No more, no less. Too much documentation nobody reads, too little documentation helps nobody.

Plan a timeline as well. Which key roles do you lose within 3 to 5 years? How much time does it take to get a new engineer productive in a complex environment? That's a question every CTO should be asking, not something for afterwards.

Knowledge transfer only succeeds if you bring in new people in time to transfer that knowledge to. Waiting until a senior has already left means opening a vacancy with nobody left to onboard the new colleague.

The EU has set itself the goal of having twenty million ICT specialists by 2030. In 2024, the gap to that target was still around 9.7 million. In the Netherlands alone, an estimated 90,000 ICT positions are open without a suitable candidate. That problem won't solve itself while you wait for the next reorganization round.

This is exactly what we work on at Doghouse: not reactively filling a vacancy when someone is already gone, but thinking ahead about which roles are becoming vulnerable. For roles like an infrastructure software engineer managing core systems, or a senior network engineer who is the only one who truly understands the network architecture, that early signal is the difference between a smooth handover and a crisis.

Structured delivery means, concretely: intake at role level, sourcing that matches what a team is really missing, and interviews that test whether someone can handle not just the technology, but also take over the onboarding path of a departing senior. No scattering CVs around and hoping one sticks.

Roles with a lot of implicit, historically built-up knowledge run the greatest risk at retirement. Think legacy architects, senior network administrators and engineers who have been on the same platform for years. Precisely those positions are the hardest to refill, because the knowledge was never systematically captured.

With more complex technical profiles, such as a senior AI engineer keeping models running in production, the same risk applies. The knowledge about why a model was trained a specific way, or why certain data sources were excluded, often sits in one person's head.

That's not theory. That's the daily reality at every team we talk to.

For hiring managers this means: don't start with the job posting, start with the question of which knowledge you'll be missing in three years. Only then does it become clear which profile you're looking for and how much time you need to onboard that person properly.

Knowledge transfer around retirement is not an HR topic you tick off with an exit interview. It's a risk that's already on your plate, even if your first senior still has years to go. If you wait until someone leaves, you buy back time at a steep price: delayed projects, expensive interim hires and knowledge you'll never get back.

Want to know which roles in your team run the greatest risk and how to get ahead of it now? We're happy to think along, no strings attached.