Guide
Interim CTO or fractional CTO?
An interim CTO fills a vacant full-time seat for a fixed period, usually four days a week or more, and leaves when a permanent hire starts. A fractional CTO is an ongoing part-time arrangement sized to the business, often one or two days a month, rising when a programme needs it.
Both are senior technology leaders brought in without a permanent hire. They solve different problems, and choosing the wrong one is expensive in both directions.
Side by side
| Criterion | Interim CTO | Fractional CTO |
|---|---|---|
| Why you are hiring | A seat is empty and work is stalling | The decisions are executive-level; the headcount is not yet |
| Time commitment | Most of the working week | A cadence you set, from monthly to weekly |
| Duration | Fixed: typically three to twelve months | Open-ended, reviewed as the business changes |
| Mandate | Full executive authority while in post | Advise, decide with you, hold suppliers and teams to account |
| Cost shape | Close to a full-time executive cost, without equity | Scales with the time you buy; stops when you stop |
| Team management | Line-manages the technical team directly | Coaches technical leads rather than replacing them |
| Exit | Handover to the permanent CTO | Step down gradually as internal capability grows |
Neither title has a legal definition, so terms vary between firms. This table describes how the two arrangements work in practice, from fifteen years of running technology organisations as a CTO, a COO and a consultancy founder. It is experience, not survey data.
How to choose
Which one your situation calls for
Signs you need an interim CTO
Your CTO has left or is leaving, there is a technical team with nobody running it day to day, and decisions are queuing up waiting for an owner. That is a full-time gap, and a two-days-a-month arrangement will not close it.
Signs you need a fractional CTO
There is no vacant seat. You have a development agency or a small in-house team, and what is missing is someone senior enough to read what they promised against what they shipped, and to set a plan the board can verify.
Signs you need neither yet
If the technical decisions still sit comfortably with a founder who understands them, and no external party is being paid on trust, you may be paying for reassurance rather than judgement. I will say so.
The two often run in sequence
An interim closes an urgent gap, then hands over to a permanent CTO. A fractional arrangement frequently follows, giving the new CTO someone independent to test decisions against for the first year.
Questions
Common questions
- Is an interim CTO the same as a fractional CTO?
- No. An interim CTO is a temporary full-time appointment covering a vacant role for a fixed period. A fractional CTO is a permanent-but-part-time arrangement sized to the stage of the business. The difference is time commitment and mandate, not seniority.
- Which is cheaper?
- A fractional arrangement costs less in total because you buy less time, not because the judgement is discounted. If the business genuinely needs a full-time technology leader, fractional is not a cheaper version of that — it is a different arrangement that will not close the gap.
- How quickly can either start?
- Both start in days to weeks, which is the main reason companies use them. A permanent CTO appointment is usually a multi-month executive search, and the business rarely has that long when delivery is already slipping.
- Can a fractional CTO become an interim CTO?
- It happens, and it should be a deliberate decision rather than scope creep. If the cadence keeps rising because the business now needs daily leadership, the honest answer is that the shape of the arrangement has changed and should be renegotiated.
- Do either of these replace a non-executive director?
- No. Both work inside the business on delivery and technical decisions. A non-executive director sits on the board outside the executive, holding it to account, and carries statutory directors' duties under the Companies Act 2006.
Sources and review
This page makes no statistical claims and quotes no market rates, because no credible published dataset exists for either arrangement. The statutory point about directors’ duties comes from the Companies Act 2006, sections 170 to 177, and is explained further on the technology NED guide .
Last reviewed:
Not sure which shape fits?
Describe what has stalled and who is currently accountable for it. I will tell you which arrangement fits, including when the answer is neither.