Compare the models
Fractional COO, consultant or interim COO?
Three genuinely different ways to buy senior operations leadership. The right answer depends on your stage, your team's strength, and how much delivery you need to delegate — not on which label is fashionable.
Side by side
The honest comparison
The rows buyers actually ask about: who owns the outcome, how much authority they carry, what it costs, and when each model earns its fee.
| Consultant / advisor | Fractional COO | Interim COO | |
|---|---|---|---|
| Commitment | A few days a month, typically workshops and reviews | 1–3 embedded days per week on a rolling basis | Full-time, usually 4–5 days per week |
| Accountability | Recommends; you and your team execute and own the outcome | Leads the operating plan with you and owns delivery alongside the team | Fully owns the function for a defined period |
| Authority | No line authority — influences through advice | Delegated executive authority agreed up front — chairs reviews, unblocks decisions | Full executive authority, often with a turnaround or transition mandate |
| Presence | Mostly off-site, dipping in and out | Embedded in the rhythm: standups, S&OP, supplier and customer conversations | Full-time on site or remote, for the duration |
| Typical duration | Open-ended, often years at low intensity | Typically 6–18 months, scaling down as the team takes over | A defined 3–12 month assignment, then exits |
| Cost profile | Lowest monthly spend, but delivery risk stays with you | A fraction of a full-time COO's £150k–£250k+ fully-loaded cost | Highest monthly cost — full-time day rates for the whole period |
| Best for | A targeted problem in a business that already executes well | Scaling manufacturers and hardware firms that need senior operations leadership before they can justify a full-time hire | Sudden leadership gaps, turnarounds, or bridging to a permanent hire |
Pricing models
How fractional COO engagements are priced
UK engagements are usually structured one of three ways. All three avoid the £150k–£250k+ fully-loaded annual cost of a permanent COO — salary, bonus, pension, employer NI, equity and recruitment fees.
Day rate
A fixed rate per embedded day, billed monthly in arrears. The most common starting point for a fractional COO engagement in the UK — simple to budget, easy to scale up or down as the stage of the business changes.
Best fit
First engagements, or where the number of days will flex month to month.
Monthly retainer
A fixed monthly fee covering an agreed number of days plus reasonable access between days. Predictable for both sides and suits a steady operating rhythm once the cadence is established.
Best fit
Established engagements with a stable weekly pattern.
Outcome-linked
A reduced base commitment with an element tied to agreed milestones — funding closed, a line commissioned, an audit passed. Used selectively; the milestones have to be genuinely within the COO's influence.
Best fit
Specific, measurable programmes such as funding readiness or a product transfer.
Standard engagement models and terms for GJM Consultants Ltd are set out on the fractional COO proposal page.
UK guidance
IR35 and the off-payroll working rules
For UK companies hiring through a limited company, IR35 is part of the model decision. Here is the plain-English position — and where to get formal advice.
- What is IR35 and does it apply here?
- IR35 (the off-payroll working rules) decides whether someone working through an intermediary — usually a personal service company — is taxed as a disguised employee. Since April 2021, medium and large private-sector clients determine the status; small companies are exempt and the determination stays with the contractor's company. GJM Consultants Ltd engages business-to-business and the status question is addressed openly at the start of every engagement.
- Why fractional COO work is typically outside IR35
- A genuine fractional engagement looks like a business supplying a service: multiple concurrent clients are possible, the COO controls how the work is delivered, there is no employment-style mutuality of obligation, and the engagement is scoped around outcomes and an operating cadence rather than a job role. Working practices — not the contract wording — are what HMRC tests, so the engagement is run to match.
- How this differs from an interim COO contract
- A full-time interim embedded for months, under the client's direction and integrated like an employee, carries a materially higher risk of being inside IR35. That risk is priced into interim day rates. Part of choosing between models is understanding the tax position honestly rather than discovering it at year end.
- What you receive at engagement start
- A clear written scope, agreed working practices, and — where your organisation is medium or large — support for your status determination statement, so the IR35 position is documented rather than assumed. For anything beyond the ordinary, take advice from your accountant or an IR35 specialist; this page is orientation, not tax advice.
Next step
Not sure which model fits?
A thirty-minute call is usually enough to rule out one model and size another. Bring your stage, your team's shape and the outcome you need in the next two quarters.