Part-time CTO Services, Compared | Fractional CTO Service

"Who signs off the architecture decision in week three, when our part-time CTO is back with his other client?"

The week-three decision is the whole comparison, and the market settles it in three different ways. A part-time CTO service is not a discount on an executive salary. It is a contract for decision rights over a share of a month, and the fee, the exposure and the exit all come from how that share is drawn. This page takes the unit of the engagement first, then the models sold under one name, then the tests that separate them.

Days on a calendar are the meter; decisions are the product

Everything priced in this market is metered in days and sold as decision quality, and the two are not interchangeable. Acentrix sets out the condition a company reaches before it engages anyone: stack, vendors and architecture chosen by whoever shouted last, compounding quietly. A retainer does not repair that by adding hours to a calendar. It repairs it by putting one identified person in front of specific decisions. Two providers can each sell two days a month and disagree completely about whether the second day goes to challenging an agency estimate or to interviewing a backend engineer. Ask what the days touch before you ask what they cost, and ask for the decision load on the contract page: how many calls a month need a senior technical view, how many of them are irreversible, and who makes them today. A day that touches nothing you could not have decided yourself has been rented.

Advisory, embedded and interim are three models at three depths

Advisory is a sounding board with on-call access and a scheduled session each month; embedded adds leadership days inside your team; interim means several days a week with hands on the work. Acentrix's published retainers price the first two at fixed monthly figures and set interim against the situation itself, with the numbers in the table below. Vention's UK CTO as a Service page runs the same ladder at eight, sixteen and twenty-four hours a week under the labels Supportive, Enabler and Intensive. Groovy Web's fractional CTO case study fits inside the embedded band at twenty hours a week for a year, and reports an engineering team growing from eight to thirty-five people with three AI products shipped in that time. DashDevs cuts the market four ways, adding a single advisory session and a project-based engagement alongside the part-time and full-time routes. TST Technology draws the line between the part-time model, a few hours or days each week, and the temporary model that covers a leadership gap or one specific project.

Model as sold	What the meter counts	What is still in place at the end	Published monthly cost	Condition it fits
Advisory	On-call hours plus one scheduled session	A short view in plain English and a set of decisions to take	£1,250	A board needs a second opinion it can act on this quarter
Embedded	Leadership days inside the team plus oversight	Roadmap, hiring bar, delivery rhythm, security posture	£2,950; USD 5,000 to 15,000 for a twenty-hour week	An engineering organisation needs a leader before it can attract one
Interim	Days per week against a mandate with a deadline	A closed funding round, a completed turnaround, a team handed over	Priced against the situation	A round, an exit, a departure or a crisis

Monthly figures in the table are published by Acentrix, and the twenty-hour band by Groovy Web. The condition column reflects the circumstances each provider sets out for its own model.

A retainer needs a standing agenda, agreed before the first month ends

A retainer with no recurring rhythm is a consultant holding a CTO title. CTOx reports its own sequence as a systems map in the first thirty days, execution through the next sixty, then a revised plan on a ninety-day cycle. Vention's page sets out board representation, technology budgeting and risk management as duties that recur. If a provider cannot say which review session it runs, how often it runs, and the three numbers examined there, the engagement drifts towards whatever is loudest that month. Those three numbers are usually the ones a board already asks for: delivery against the plan, spend against the technology budget, and the count of open risks with an owner. The rhythm is the spine of the service; without it, the decision rights you paid for have nowhere to be exercised.

Continuity separates the models more cleanly than price does

Groovy Web states that its goal is to work itself out of a job, and reports promoting internal technology leads, preparing the engineering playbooks and documenting processes before handover. Acentrix's FAQ says the same in fewer words: it will help the client hire a full-time CTO when the client is ready, and it calls both outcomes wins. Ask what stands on the last day that was not there on the first. A retainer that leaves no document behind has been an operating expense with a leadership title on it, and the next hire inherits the same gaps.

Measure the fee against the gap it closes

Vention's page records that an in-house CTO hire typically runs four to six months across search, interviews, negotiation and notice, on top of salary, bonuses, benefits and overhead. Leadership Services sets the floor of a UK full-time CTO salary at £120,000 and reports that a part-time contract can begin straight away, with no three or six-month notice period or gardening leave to work through. The comparison that counts is the cost of the decisions left unmade during a recruitment, set against the fee for somebody who can start on Monday. A recruitment that runs four to six months is a delay as much as a cost, and in that window the architecture gets chosen by default. Where a company has to settle an architecture choice before a funding round closes, the fee is the smaller number by a wide margin.

Risk lands with whoever owns the decision

Advisory work recommends; embedded and interim work decide. A recommendation you decline costs you a retainer. A decision the provider owns and gets wrong costs you the rebuild. Glyn Roberts, Vention's CTO for UK digital solutions, places the weight where it belongs on that same UK page.

Remember: A core part of the CTO role is making tough decisions and thinking strategically, both in the moment and over the longer term. Without a clear strategy guiding every move and keeping the big picture in view, things can unravel very quickly.

Read that against a costing. A provider that will not say which decisions it owns alone, and which come back to you, has not priced the risk it is taking on. Put the split on the contract page before the first bill, because the engagement is governed by it whether or not it appears on paper.

Four points that make two proposals comparable

Ask each provider to set out the decisions the engagement will own alone, the decisions that come back to you, the document produced at the end, and who steps in if the individual doing the work leaves. DashDevs frames the proposal as the paper that sets out what the service includes and what it costs, which is where those four points belong. Two proposals become comparable the moment all four appear on the same page. Until then the lower fee wins by default, and the company pays the difference later, in decisions taken with nobody senior in the room.