The two titles get used as if they mean the same thing. They don't. Both bring in a senior outside technology leader, but they solve different problems, and choosing the wrong one costs you either money or momentum.
The simplest test is one question: does engineering have an owner today? If the answer is no, you need interim cover. If the answer is yes but they need help with the bigger calls, you need a fractional CTO.
What an interim CTO does
An interim CTO steps into an empty seat. The previous CTO has left, been let go, or never existed and the company has suddenly outgrown that. Someone has to make decisions now: who works on what, which release ships, what the board hears, which hires go ahead.
The interim CTO owns all of that for a defined period. The job is to keep the team shipping, stop decisions from stalling, and get the company ready for a permanent hire. A good interim CTO also helps run that search and hands over cleanly to the person who gets the job.
Because the role is about ownership, it takes a lot of time. In practice that means three or more days a week, close to full time.
What a fractional CTO does
A fractional CTO joins a company that does not need a full-time CTO yet, or cannot justify one. The team can run day to day. What is missing is senior judgment on the decisions that are expensive to get wrong: architecture, hiring the first senior engineers, build vs buy, security and compliance, and how technology is explained to investors.
The fractional CTO works one, two or three days a week on an ongoing basis, inside your leadership team rather than as an outside advisor. There is no search running in the background. The arrangement lasts as long as it is useful, and ends when the company is ready for a full-time leader.
When each one fits
Interim fits when:
- Your CTO has just left and nobody else can own the technical side.
- A portfolio company loses its CTO in the middle of a value-creation plan, and the sponsor needs continuity while it searches.
- A major event is close, such as a fundraise, an acquisition or a big migration, and the company cannot afford a leaderless few months.
- You are pre-seed to Series B and a full-time CTO would be too early or too expensive.
- You are a non-technical founder who needs a senior technical partner in the room.
- You have a capable tech lead or head of engineering who needs someone senior above them, not a replacement.
How long each one lasts
An interim engagement has an end date built in. It runs until the permanent CTO is hired and settled. On our private equity page we describe this as 6 to 12 months of cover while the board runs a full-time search, and the search itself often takes 6 to 9 months.
A fractional engagement has no fixed end. Most of ours run 6 to 18 months, and some run much longer. Aesthetic Record kept us as fractional CTO for 4 years while it grew to more than 4,000 US clinics. The point of a fractional engagement is to stay useful, not to fill a seat until someone else arrives.
What each one costs
Kompella publishes its prices on the fractional CTO services page:
| Tier | Monthly fee | Time |
|---|---|---|
| Advisory | $8,000 | 1 day a week |
| Fractional | $15,000 | 2 days a week |
| Embedded | $25,000 | 3+ days a week |
Fractional work usually sits on the Advisory or Fractional tier. Interim cover needs the most time, so it sits on the Embedded tier. For private equity portfolio companies the scope and reporting are heavier, and our embedded portco work starts at $30,000 a month.
The comparison founders should make is not interim against fractional. It is the cost of the cover against the cost of a leaderless team: decisions that stall, engineers who leave, and a roadmap that drifts while you search.
How to switch from one to the other
The two models work well in sequence, and the switch is easier than most founders expect.
Interim to fractional. This is the most common path. The interim CTO steadies the team, makes the overdue decisions and helps you hire. Then, either before the permanent CTO starts or once they are settled, the engagement drops to one or two days a week. The permanent hire gets a senior sounding board instead of a cold handover.
Fractional to interim. This happens when the situation changes fast: your head of engineering resigns, or a fundraise or acquisition brings due diligence forward. Because the fractional CTO already knows your codebase, team and roadmap, stepping up to three or more days a week takes days rather than months.
Two things make either switch smooth:
- Month-to-month terms. If you have to sign a new contract to change the number of days, the switch will be late. With our tiers, changing between Advisory, Fractional and Embedded is a change of tier.
- Written records from day one. Architecture decisions, hiring notes, vendor contracts and the list of commitments made to customers should be written down as you go. That is what lets the next person, interim, fractional or permanent, pick up without starting over.
A note for private equity
Sponsors often need both models across a portfolio at once: interim cover at one company whose CTO has left, and fractional support at another that is growing into the role. We currently serve as fractional CTO to Landocs Private Equity in Tel Aviv, covering diligence before deals close and value creation after. The private equity page explains how we structure interim cover for portfolio companies.
The short version
If the CTO seat is empty, you need interim cover: someone who owns the team until the permanent hire starts. If the seat can stay empty for now but the big decisions need a senior voice, you need a fractional CTO. Use month-to-month terms so you can move between the two as things change.
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