A CEO calls me. He’s looking for an “interim CTO.” We talk for twenty minutes. What he describes: someone who comes in two days a week, challenges technical decisions, helps with hiring and prioritization. His long-standing CTO has left, the team is managing delivery, but no one is steering the direction.
What he’s describing is not an interim. It’s a fractional.
The difference: an interim is someone full-time. Budget multiplied by three. Daily presence. And often, a very different profile.
This confusion is common — and costly. Not because CEOs aren’t sharp, but because no one has taken the time to define these terms clearly. The market often uses them interchangeably. They’re not the same thing.
The interim CTO: temporary replacement, full-time
The interim CTO fills a gap. They come in, take operational control of technical leadership, manage teams day to day. It’s a fixed-term full-time position.
This model makes sense in one specific situation: your CTO has left, recruiting a replacement will take six to twelve months, and someone needs to hold the role in the meantime.
It’s full-time, physically present, priced accordingly. Expect between €15,000 and €25,000 per month depending on the level. And the interim CTO needs time to understand the organisation before they can contribute — two to four weeks of ramping at minimum.
This model doesn’t make sense if your problem is strategic rather than operational. An interim in an organisation that already has a CTO creates immediate governance friction. And if what you’re looking for is an external perspective, continuous presence isn’t necessary.
I don’t offer the interim CTO. Not because it’s not a legitimate model — it is. But because it requires full-time availability that I don’t have.
The advisory CTO: specialist input, without execution
The advisory CTO isn’t inside the organisation. They intervene occasionally — a half-day per month, a strategic committee, a quarterly architecture review. Their role: bring a high-level external perspective, challenge major decisions, offer a viewpoint the internal team can’t have about itself.
This model makes sense when you already have a solid CTO or head of engineering, and what you’re looking for is a quality second opinion on structural decisions.
This is not an execution model. The advisory CTO doesn’t manage your backlog, doesn’t hire your team, isn’t involved in delivery. They advise. That’s their value — and their limit.
The fractional CTO: regular strategic leadership, part-time
The fractional CTO sits in between. They’re involved regularly — two days a week, ten days a month depending on the need — but isn’t there every morning. They’re part of the organisation without being an employee.
Their value: continuity without the full-time cost. They know your stack, your team, your constraints. They can make strategic technical decisions, hire, challenge architecture, represent technical leadership in committees. This isn’t a one-off external perspective. It’s a regular partnership.
This model makes sense in three situations: your CTO has left and you don’t yet know if you need a full-time replacement, your CEO or lead dev is making tech decisions by default, or your existing CTO is overwhelmed and needs a strategic partner.
What the fractional doesn’t do: it doesn’t replace an operational CTO managing teams of twenty people who need a manager present every day. Beyond a certain size and organisational complexity, full-time is unavoidable.
This is the model I offer. Two to four days per week depending on the need, minimum six-month engagement for the value to be real. To understand the specific contexts where a Fractional CTO adds value, this article details the profiles who benefit most →
How to choose — the four questions to ask
Before posting a job or calling a consultant, four questions.
Is your need operational or strategic? If you need someone who manages teams day to day, arbitrates conflicts, handles incidents — that’s operational. Interim or full-time CTO. If you need someone who makes the right architecture and roadmap decisions, aligning tech with business — that’s strategic. Fractional or advisory.
Has your CTO left or are they simply overloaded? If your CTO has left, the question is: how quickly do you need someone and for how long? If your CTO is still in place but overwhelmed, what you need is a partner, not a replacement.
How big is your tech team? Under ten developers, a fractional generally covers the needs. Between ten and twenty, it depends on existing maturity and organisation. Beyond twenty, full-time is often necessary.
What’s your time horizon? If you have six to eighteen months ahead — transformation, fundraising, recruiting a permanent CTO — the fractional is the right format. If it’s an emergency situation with a three-month horizon, interim is more appropriate.
So, concretely
The next time you’re looking for a “CTO outside the usual setup” — interim, fractional, advisory, whatever the word — start by asking the operational/strategic question. The answer shapes everything else.
If you need someone who defines technical direction, makes architecture decisions, hires and structures the team — but doesn’t have to be there every morning — fractional is probably what you need.
If you’re not sure, that’s often a sign the problem hasn’t been framed clearly enough yet. A thirty-minute call is usually enough to clarify it — before committing to anything.
For a full picture of what a Fractional CTO engagement → covers in practice.