Fractional CTO, full-time CTO, or technical advisor?
Three ways to get senior technical judgement into a company that does not have it. What each one is actually for, and the point at which you should switch.
The short answer
Hire a full-time CTO when engineering decisions are daily and you have a team to lead. Use a fractional CTO when the decisions are weekly and consequential but there is not yet a team to justify a salary. Use an advisor when you have competent people who occasionally need a second opinion. The most expensive mistake is hiring a full-time CTO before there is anything for them to run.
The question is usually framed as a budget one. It is really a frequency one: how often does someone need to make a technical decision that is expensive to reverse?
The short answer
| Advisor | Fractional CTO | Full-time CTO | |
|---|---|---|---|
| Decision frequency | Occasional | Weekly | Daily |
| Owns outcomes | No | Yes, within scope | Yes, entirely |
| Typical engagement | A few hours a month | Days per month | Full time |
| Good for | A second opinion | Architecture, hiring, vendor oversight | Leading a team and a roadmap |
| Ends when | You stop asking | You hire the permanent person | It does not |
Technical advisor
Someone experienced you can call. They will tell you whether a decision sounds reasonable, whether a candidate is plausible, whether a vendor estimate is mad. What they will not do is own the outcome, and that boundary is usually explicit.
This works when you already have competent people making good decisions, and you want a sanity check at the edges. It does not work as a substitute for leadership, because an advisor is not in the room when the decision is actually made.
Fractional CTO
Someone who takes responsibility for the technical decisions, at a fraction of a full-time load. Architecture, platform choices, technical hiring, and holding vendors to a standard. They are in the room and their name is on the call.
The model fits a specific and common situation: the decisions are consequential and happening weekly, but there is not yet an engineering team large enough to occupy a full-time leader. Hiring a full-time CTO into that situation usually produces a well-paid person doing individual contributor work and getting restless.
The thing to check when buying it: is the engagement sized in days, or is it a retainer for being reachable? The second is much harder to evaluate, and the incentive runs the wrong way.
- Good signs: sized in days per month, a written view on architecture, willing to say what they do not know.
- Bad signs: priced for availability, no artefacts produced, no plan for the engagement ending.
Full-time CTO
The right answer once there is a team to lead, a roadmap to own, and technical decisions arriving daily. At that point fractional stops making sense: the context load is too high to hold part time, and the team needs someone present.
The common mistake is hiring here too early, usually because a board or an investor suggested it. A CTO with no engineers is an expensive senior engineer, and the good ones leave.
The switching points
Two signals, and they are reasonably reliable.
- 1Advisor to fractional: when you notice decisions being made without them because there was not time to ask.
- 2Fractional to full-time: when you have three or more engineers, or when the fractional person is being pulled into daily work rather than decisions.