Your CTO gave notice last week. The search for a replacement will take three to six months if it goes well. In the meantime the engineers still need someone to approve the architecture change, the agency still needs managing, and your board wants to know who is accountable for the technology. Someone suggests an interim CTO, someone else suggests a fractional one, and the quotes you get back differ by a factor of two or three.
The short answer: an interim CTO is a near-full-time leader for a fixed period and costs close to a full senior salary, often more, prorated by the month. A fractional CTO covering the same gap at one or two days a week costs a fraction of that. Neither is cheaper in the abstract. The right choice depends on how much of the CTO's actual job has to keep running while you search, and most companies under Series A need less cover than the panic of the resignation suggests.
Interim and fractional are different products
The words get used loosely, so pin them down before you compare prices.
Interim means someone steps into the role, close to full time, for a defined period, typically three to twelve months. They run standups, manage the team day to day, own incidents, and sit in leadership meetings. They are filling the seat.
Fractional means a senior leader who works with you part time on an ongoing basis, typically one to three days a week. They own the decisions and the direction but not the daily operation. They are covering the judgment, not the seat.
An interim engagement is priced like a short senior hire, with a premium for the temporary nature and the speed of availability. A fractional engagement is priced like a retainer. Comparing them on monthly cost alone is comparing a full-time role with a part-time one.
What the departing CTO was actually doing
Before choosing, list what the CTO did in a normal week and sort it into three piles.
- Daily operation. Running standups, unblocking engineers, reviewing pull requests, being on the incident rota. In a team of three to eight engineers, a senior engineer or tech lead can usually absorb most of this for a few months, especially with a raise or a title.
- Decisions and direction. Architecture calls, vendor choices, hiring decisions, the roadmap trade-offs. This is the part that cannot pause and cannot easily be delegated to someone junior.
- External accountability. The board, investors, enterprise customers asking security questions, the technical half of a raise.
If most of the week was daily operation and you have a credible senior engineer, fractional cover for decisions and external accountability is usually enough. If the CTO was the only senior person and the team is junior, or if you are mid-incident or mid-migration, you may genuinely need someone in the seat.
An illustrative comparison
Suppose the departing CTO was paid around $200,000 a year, roughly $17,000 a month.
An interim leader at near-full-time for four months would commonly cost at or above that monthly figure, because you are paying for immediate availability and a short commitment. Over four months, that is the larger number.
A fractional CTO at two days a week for the same four months would commonly cost well under half of it, and you would add a modest stipend or title bump for the senior engineer who picks up daily operation.
The gap is real. The question is whether the extra days buy you anything you need. They do if the team cannot run itself. They do not if what you were really missing was someone to make the hard calls and talk to the board.
The hidden costs on both sides
Interim cover has a hidden cost when the interim is good at running the team but not invested in the future. They keep things stable, defer the hard decisions to the permanent hire, and you arrive at month five with a backlog of choices nobody made.
Fractional cover has a hidden cost when the team was more dependent on the departing CTO than anyone admitted. Two days a week is not enough if every pull request was waiting on one person. You find out within two to three weeks, and the fix is usually to raise the days for a month, not to switch to interim.
Both have a hidden cost if the cover person is also a candidate for the permanent role and nobody said so. It distorts every decision they make. Ask directly.
Use the gap to make the permanent hire better
The best use of cover during a search is not only to keep the lights on. It is to work out what the permanent hire actually needs to be. A few months with an outside senior person will tell you whether you need a hands-on CTO, a VP of Engineering, or a strong lead engineer who reports to the founder. CTO or VP of Engineering is the longer version of that choice.
Some companies discover in the gap that a fractional arrangement was enough all along, and that the full-time role can wait until a later stage. Fractional or full-time CTO: run the numbers first is worth reading before you sign the search firm's contract. If the departure is happening close to a raise, your technical cofounder left before the raise covers how investors will read it.
What I would do
For most seed and early Series A companies with a senior engineer on the team: promote or stipend that engineer to cover daily operation, bring in fractional cover at one to two days a week for decisions and external accountability, and review after four weeks. Raise the days if the team is stalling. Move to interim only if the team genuinely cannot run without a full-time leader in the seat.
My own terms for this kind of cover are on the pricing page. If your CTO has just resigned and you want to work out how much cover you actually need, book a call.
FAQ
Is an interim CTO more expensive than a fractional CTO?
Per month, yes, usually by a wide margin, because an interim works close to full time. Over a given gap, the fractional option is cheaper if the team can run day to day without a full-time leader.
How long does an interim CTO engagement usually last?
Typically three to twelve months, often tied to the length of the search for a permanent hire plus a short overlap.
Can a fractional CTO cover the gap after a CTO resigns?
Often, yes, if a senior engineer can absorb daily operation. The fractional CTO covers architecture, hiring, vendors, and board accountability.
Should the interim or fractional CTO be a candidate for the permanent role?
It can work, but say so openly at the start. An undisclosed candidate makes different decisions from a neutral one.