Bring in an interim COO when a practice has an acute, time-bound operating problem that needs senior hands now: an operations seat that has emptied, a practice-management migration that has stalled, an acquired firm to integrate by a date, or a turnaround where the owner has lost control of workflow and cash. An interim is in the firm two or three days a week for a fixed term of three to six months on a day rate, and the term should be built around a written brief, decision rights agreed at the start, a 30-60-90 day plan and a final month given over to handover. If the problem is chronic rather than acute, a fractional retainer is the better shape.
Acute, not chronic
The test for interim cover is simple to state and easy to get wrong under pressure. An interim solves an acute problem: something has happened, or is about to, and the firm needs senior operating capacity for a period to get through it. A fractional COO solves a chronic one: the firm has never had an operations function, and needs one built and kept. The two are compared properly in interim COO vs fractional COO. This guide is about recognising the acute case when you are in it.
Owners tend to misdiagnose in one direction. A bad quarter feels like a crisis, so they look for an interim, when what they actually have is a firm that has outgrown how it runs and will have the same quarter again next year. The opposite error is rarer but costlier: treating a genuinely acute problem, a resignation or a stalled migration, as something a weekly session can absorb, and finding six months later that it has not.
The four situations
1. An operations seat has emptied
The practice manager, operations director or the partner who quietly ran everything has resigned, gone on long-term leave or retired. A permanent replacement is three to six months away even if the recruitment goes well. In the meantime workflow, capacity, deadlines and the team need holding by someone senior, and ideally the seat should be handed to the permanent hire in better order than it was left in. Two days a week is usually enough to cover the seat; the third day is what turns cover into improvement.
2. A programme has stalled
The move to new practice-management software, the roll-out of a workflow system, the restructure into pods: it was meant to be live by a date, it is not, and the reason is that nobody inside the firm has two clear days a week to own it. An interim owns it to completion. The brief here should be unusually specific, with a definition of done and a date, because a programme with neither is how it stalled in the first place.
3. An acquisition needs integrating
The deal has completed, and the firm now has two ways of onboarding clients, two workflows, two review standards, two sets of roles and two pricing models. Left alone the two firms carry on as two firms under one name, and the synergies in the deal model never appear. Integration to one operating model, by a date, without losing the people or the clients who came with the acquisition, is one of the most common and most valuable interim briefs in the sector.
4. The owner has lost control
Less common and less comfortable to name. Lock-up has stretched, the deadline list is red, two senior people have left in a year, and the owner is working seventy-hour weeks to hold it together. This is a turnaround, and it needs senior operating hands in the building at intensity, not a weekly session. The interim stabilises workflow and cash first, then rebuilds, then hands over to whatever the firm needs next, which is often a fractional retainer.
What a good term contains
| Element | What it is | Why it matters |
|---|---|---|
| A written brief | What is being covered or delivered, by when, and what done looks like | An interim without a brief becomes a permanent fixture nobody decided to hire |
| Decision rights | What the interim decides alone, what the owner decides, what needs the partners | Cover that has to ask permission for everything is not cover |
| A 30-60-90 day plan | Workstreams, owners inside the firm, milestones | Makes the term visible to the partners and keeps the interim honest |
| A weekly operating log | Decisions taken, fires put out, risks, what needs the owner | The owner stays informed in five minutes a week without being pulled back in |
| Processes written as they change | SOPs updated in the firm’s own library, in the week they change | The alternative is a handover document written in the last week that nobody reads |
| A final month of handover | Named owners for every workstream, a handover pack, the plan handed to the firm | This is the difference between cover that leaves a gap and cover that leaves a function |
How to contract it
Interims in the UK are engaged through their own company, an umbrella, an agency or on a fixed-term employment contract, and each carries different tax and cost consequences, set out in the comparison guide. The simplest arrangement for a small practice is a direct business-to-business service contract with the interim’s firm, invoiced monthly on days worked plus VAT, with no agency margin because there is no agency. That is how Optivo’s Interim COO is contracted: from £1,200 + VAT a day, two or three days a week, three to six months, with the last month given to handover.
The one thing that decides whether it was worth it
Not the day rate, and not even whether the programme shipped. It is whether, three months after the interim left, the firm is still doing what was built. That is decided in week one, not in the last week: by whether processes are written into the firm as they change, whether each workstream has an owner inside the firm from the start, and whether the term was designed to end. An interim who is indispensable on the last day has failed at the part of the job that matters most.
Common questions
How quickly can an interim start?
Faster than a hire and slower than a phone call. Optivo can usually start within two weeks of agreeing the brief, which is the time it takes to set up systems access, agree decision rights and meet the team. A recruitment for the same seat typically takes three to six months.
Should the interim be in the office or remote?
In the office on the agreed days, as a default. Interim cover is about being where the work is stuck: chairing the operations meeting, sitting with the team while a new system beds in, seeing the review queue rather than hearing about it. Video works for the days in between, not for the days in the firm.
What happens if the work needs longer than the term?
The term can be extended by agreement, but an extension should be a decision, not a drift. If the reason is that the brief was bigger than it looked, extend it with a revised plan. If the reason is that the firm cannot yet run without the interim, that is a handover problem, and the fix is to spend the extension on handover rather than on more of the same.
Can it turn into an ongoing retainer?
Often it should. Once the acute work is done, a fractional retainer keeps the operating rhythm in place at a fraction of the intensity and cost. With Optivo it is the same person, so the step down from interim to the Monthly COO needs no re-learning.
Where does your firm actually stand?
Score it across the ten things a COO would look at first. Three minutes, an honest read on where you’re strong and where you’re exposed, and a 90-day plan for the areas holding you back.
Or book a confidential call if you’d rather just talk it through.