Interim CTO: what it is, how long it runs and what it costs
An interim CTO is a senior engineering leader who runs your tech org full-time for a fixed stretch, usually while you recruit the permanent one. That's a different purchase from a fractional CTO, who works a day or two a week with no end date. Confuse the two and you'll either pay full-time money for a part-time problem, or put a part-timer in a seat that needs someone there every morning.
When a company hires an interim CTO
Four situations cover nearly every placement.
- The CTO left. Your engineers need someone to report to on Monday, and a proper search takes months. KORE1 describes the role as a full-time CTO "for six to nine months after a CTO leaves".
- The hire is coming but hasn't signed. The interim keeps the roadmap moving and sits in on the final interviews.
- You're raising, or being diligenced. Atta names "companies between permanent CTOs or in active fundraising" as the typical buyer.
- Something's on fire. The product is late or the architecture is shaky, and someone senior has to take over for a set period. If the product itself is the problem, the first week is a software project rescue sprint.
That last one is where the war stories come from.
How long an interim CTO stays
Three to nine months, by most accounts. KORE1 says six to nine after a resignation. Fractionus stretches it to four to sixteen months at 45 to 50 hours a week. CodeStringers lands on three to nine for most engagements, "which lines up with how long it takes to recruit a permanent technology executive". So the clock is your hiring clock. Start recruiting the week the interim starts (nobody recruits faster once the seat feels covered), and the term sorts itself out.
Interim CTO vs fractional, part-time and CTO as a service
ZP Ventures gets it into one line: "interim is full-time but temporary. Fractional is part-time but often longer-running." The rest of the vocabulary:
- Interim CTO: full-time, fixed term, fills an empty chair, ends with a handover to the permanent hire.
- Fractional CTO: part-time and open-ended, a day or two a week, at a company that has never had a full-time CTO. Deepsel's fractional CTO also brings the engineers who do the building.
- Part-time CTO: the same purchase as fractional under a different name, sold by the hour or the day. Here's what a part-time CTO costs and where the model runs out.
- CTO as a service: an agency's subscription package, advice bundled with development hours. Ask any CTO as a service provider who's on the hook for the result.
How much an interim CTO costs
You're paying for every working day, so the monthly bill beats any part-time model. The published US figures, each from one vendor's own page (so treat them as asking prices, not averages): KORE1 (September 2026) puts a full-time interim CTO at $25,000 to $45,000 a month and interim executive day rates at $1,200 to $2,400. CTO on Demand (July 2026) and Vozwin (September 2026) both say $20,000 to $40,000 a month. Atta (July 2026) says $15,000 to $30,000.
The big interim executive firms don't publish prices at all. Business Talent Group and Korn Ferry both run interim CIO/CTO practices and quote per engagement. InterimExecs says it plainly: "There is no off-the-shelf rate card for interim execs." Expect a conversation before you get a number.
Hourly, day-rate and retainer ranges for the part-time side are in our guide to fractional CTO cost.
What a good interim CTO hands over
An interim leaves on a date, so judge one by what's still there the morning after. Write these into the contract:
- Architecture and system docs a new CTO can read in a day.
- Runbooks and access: deployment, incident response, backups, and every credential in accounts your company owns.
- A written team assessment: who's strong, who's at risk, who to hire next.
- A roadmap with the trade-offs spelled out, so the permanent CTO inherits the reasoning along with the tickets.
- A hiring brief for their own replacement, plus time in the interview loop.
Skip the handover clause and you'll pay for the same discovery twice.
Deepsel's version for startups
We don't sell interim placements. What we sell is a fractional CTO engagement for startups, which is a different animal. For $15,000 a month, month to month, a senior engineer (we call the role a Fractional Founder) makes the architecture, roadmap and product decisions, builds the product with the team, demos working software every two weeks, sits in your investor and tech-diligence calls, and sends you a plain-English scorecard each month. A typical startup MVP ships inside one to two months. Then you step back to $0 a month, keep the code, docs and roadmap in your own accounts, and bring the same team back when you need them.
It's part-time and it's built for startups. Nobody from Deepsel will be in your office every weekday. A forty-person engineering org whose CTO just resigned needs an interim firm. A founder who already has a technical lead needs hands, and a CTO retainer is the wrong product for that.
Interim CTO FAQ
What is the difference between an interim CTO and a fractional CTO?
Hours and term. An interim CTO is full-time and temporary: five days a week for a fixed stretch, usually three to nine months, covering a seat that's empty. A fractional CTO is part-time and ongoing, one or two days a week with no end date. Interim costs more per month because you're paying for every working day.
How much does an interim CTO cost?
Vendor-published US figures run $15,000 to $45,000 a month. KORE1 quotes $25,000 to $45,000, CTO on Demand and Vozwin $20,000 to $40,000, Atta $15,000 to $30,000. KORE1 puts day rates at $1,200 to $2,400. The large interim firms publish no rate card and quote per engagement, so expect a conversation before you get a number.
How long does an interim CTO engagement last?
Three to nine months is what most providers quote, and six to nine is the common answer after a CTO resigns. InterimExecs, for example, lets either side end the contract on 30 days' notice.
Should a startup hire an interim CTO or a fractional CTO?
Interim if a CTO just left and there's a team that needs a leader every day while you recruit. Fractional if you have no technical lead and need the product built; pick one who also builds, so you're left with code, docs and a roadmap you own. Either way it's a bridge. As u/JimDabell put it on r/startups: "A fractional CTO isn't an alternative to a full-time CTO, it's a stepping stone."
If your gap is a startup with no technical lead rather than an empty executive chair, read how Deepsel's fractional CTO service works and what it costs, or book a free 30-minute call with Tim. You'll leave with an honest technical read either way.