Fractional vs Interim vs Virtual CTO
Vendors sell these four labels as if they were interchangeable. Two things actually separate them: how much of the week you get, and whether the person is passing through or staying. Both change what you can hold them accountable for.
A fractional CTO works part-time but on an ongoing basis, embedded in your team and accountable for technical outcomes, while an interim CTO works full-time for a fixed period to bridge a departure or a search. A virtual CTO is a fully remote arrangement, usually closer to advice than to hands on the work, and CTO-as-a-Service is a productized subscription that an agency often staffs from a bench rather than assigning one named person. Oleg Sotnikov works fractionally: one accountable person, a few days a week, month-to-month at $5,000–10,000 per month, with advisory from $3,000.
What Each Label Actually Means
Definitions first, then the situation each one suits.
Fractional CTO
Part-time but ongoing. You buy a few days a week of one senior person who stays embedded long enough to own architecture, hiring, and delivery, and no end date is built into the arrangement. Best for: companies that need senior technical ownership every week and cannot justify a $200,000+ salary.
Interim CTO
Full-time but temporary. Someone takes the seat with a start and an end date, usually to cover a departure or hold the function together while a permanent search runs. Day rates are the common billing model here, particularly in the UK. Best for: a vacant CTO seat that cannot wait out a hiring process.
Virtual CTO
Fully remote, and in practice lighter-touch. The label describes where the person sits rather than what they own, so most virtual CTO offers land closer to advice than to running delivery: a standing call, architecture review, input on vendors and hiring. Best for: a founder who needs a senior second opinion, not a second pair of hands.
CTO-as-a-Service
A productized subscription: fixed tiers, a scope sheet, a monthly price. It is often delivered from an agency bench rather than by one named person, so ask who is assigned, whether they change, and what happens to your context when they do. Best for: buyers who want procurement-friendly packaging and are comfortable with a rotation.
Which One Do You Need?
Five situations that come up most, and the model that fits each.
Your CTO just resigned, the team is mid-release, and nobody is holding the plan.
Interim CTO
You need a full week of attention now, and a defined handover once the permanent hire lands.
You need senior technical ownership for the foreseeable future, two or three days a week: architecture, hiring, vendor calls.
Fractional CTO
Ongoing accountability without a full-time salary. This is the arrangement I take on.
You want someone to pressure-test decisions on a call, but your team can execute them.
Virtual CTO or advisory
Judgment on a schedule. Advisory starts at $3,000/month and the hands stay yours.
You are comparing three agencies selling CTO-as-a-Service subscriptions.
Read the fine print
Ask for the named person, how many other clients they carry, and what happens when they get reassigned. A rotation is a different purchase from a person.
Something specific is on fire: a stalled release, a security scare, due diligence in two weeks.
Scoped work first
A bounded engagement with a deliverable beats a retainer you have not tested yet. The $5,000 Team & AI Audit exists for this.
I run the fractional model: one person, a few days a week, month-to-month. If your situation points somewhere else on this list, I will say so on the call instead of selling you a retainer.
Frequently Asked Questions
What is an interim CTO?
An interim CTO is a full-time technical leader hired for a defined period, usually to cover a departure or hold the function together during a search. They take the seat, run the team, and hand over when the permanent hire arrives. Day rates are the common billing model, particularly in the UK market. The engagement is designed from the start to end.
What is the difference between a fractional CTO and an interim CTO?
Time, not seniority. An interim CTO is full-time and temporary: the whole week, with a known end date. A fractional CTO is a part-time CTO with ongoing ownership: a few days a week, for as long as it stays useful. Hire interim when a seat is empty and the work cannot wait; hire fractional when you need senior technical judgment every week but not forty hours of it.
What is a virtual CTO, and how is it different from CTO-as-a-Service?
A virtual CTO is a remote arrangement, usually advisory: a standing call, architecture and hiring input, no hands on delivery. CTO-as-a-Service describes the packaging instead of the working model: a subscription with tiers and a scope sheet, frequently staffed from an agency bench. The practical difference is accountability: with a virtual CTO you at least know whose calendar you are on, while a service tier can be reassigned to whoever has capacity that month.
Which model costs what?
Market fractional retainers run $8,000–25,000 per month, against $200,000+ per year plus equity for a full-time CTO, before you count the team underneath. Interim work is usually quoted as a day rate, and because it is full-time for the duration, it is the most expensive of the four while it runs. My own figures: $5,000–10,000 per month for fractional, from $3,000 for advisory, and $5,000 fixed for the Team & AI Audit.
Which model do you offer?
Fractional, and only fractional. One accountable person a few days a week, month-to-month at $5,000–10,000 per month, or advisory from $3,000 if you need judgment rather than delivery. Most engagements start with the $5,000 Team & AI Audit: five business days, a written report, and a walkthrough call, with no obligation to continue. I do not take interim seats and I do not staff work from a bench.
Tell Me What's Actually Happening
One call: what you need, which of these four models fits it, and whether I am the right person for the job.
Month-to-month, cancel anytime. 3 client slots open for 2026.
Related reading
How fractional leadership works in practice, and what it does to a team.
