At some point most founder-led businesses hit the same wall. You need senior expertise in a function (sales, marketing, operations) that's beyond what you or your current team can provide. And you've got two obvious options: hire someone full-time, or bring in a fractional executive a few days a month.
The usual way this gets decided is by cost. Full-time is expensive, fractional is cheaper, so fractional wins. But that's a shallow reading of the maths, and it misses the question that actually matters. Let me walk through the real version.
The surface comparison
On the face of it, the numbers favour fractional easily.
A full-time commercial director, marketing director, or operations lead at the level a growing business actually needs will cost six figures, often £100,000-plus once you add national insurance, pension, bonus and the rest. Before any of that, you've got a recruitment process that can take months and a real risk of hiring the wrong person, which is its own expensive problem.
A fractional executive, the same seniority, a few days a month, typically runs in the region of £4,000 to £6,000 a month. You can start in weeks rather than months. And you're not carrying the full salary of a senior person for a role that may not need forty hours a week of their time.
So if the question is "which costs less?", fractional wins comfortably. But that's the wrong question.
The question that actually matters
Here's what the cost comparison misses: in both cases, you might be buying expertise that walks straight back out the door.
I learned this the hard way, years ago, with a full-time hire. I ran a business selling exhibition stands and brought in a sales manager to run a team of five. He was good. The numbers climbed, things ran smoothly, and for a few years I didn't think about it. It was all built on his instinct and experience, none of it written down, because it didn't need to be. It just worked.
Then he left, as good people do. And the moment he did, I realised there was nothing left in the building. The team knew what they were doing only because they'd absorbed it from him over years. There was no process, no documented way we sold, no objection-handling guide, no onboarding material. It took around nine months to recover: find a replacement, wait out his notice, and have him learn everything from scratch by sitting in the office listening to live calls.
That was a full-time hire. Now apply the same risk to a fractional executive, who is temporary by design. They arrive, apply a career's worth of expertise, things improve, and then the engagement ends and they move on to the next client. If nothing was systematised, the value leaves with them, just faster and more predictably than with a permanent hire. You rented a brain. You kept nothing.
So the real question isn't "full-time or fractional?". It's: whichever I choose, what will be left in my business when this person is gone?
Reframing the comparison
Once you ask that question, the comparison changes shape entirely.
A full-time hire who keeps everything in their head is a single point of failure on a six-figure salary. They feel safe because they're always there, until the day they aren't, and you discover how much of the business was actually them.
A fractional executive who simply "does the work" for a few days a month is cheaper, but carries the same risk in sharper form: they're leaving by definition, often sooner, and if they haven't built anything that stays, you're back to square one when they go.
But there's a third option that most people don't frame as an option at all: buying the system rather than the person. Engaging senior expertise specifically to build something your business owns and keeps, a documented process, a working machine, capability that stays in the building when the expert leaves. Same expertise, but it compounds instead of evaporating.
That's the genuine choice. Not full-time versus fractional. Rented expertise versus owned capability.
How to decide
So, practically, how should a £1–10M founder think about it?
If the role genuinely needs a full-time person, forty hours a week, ongoing, embedded, then hire. But hire with eyes open: insist that what they know gets documented as they go, so the business owns the system even if the person leaves. Don't let critical knowledge live in one head. That's the mistake I made, and it cost me nine months.
If you need senior thinking but not a full-time job's worth, fractional makes sense, and the cost argument is real. But choose a fractional engagement that leaves something behind. Ask directly: at the end of this, what will my business own? If the answer is "a working, documented system my team can run", that's expertise that compounds. If it's "you'll have to hope your team remembers what they learned", you're renting a brain and you'll be back where you started the day it ends.
The test for either is the same simple question: when this person is gone, what's left? Run every hiring and engagement decision through it.
The bottom line
The cost comparison everyone starts with, full-time's six figures versus fractional's few thousand a month, is real but shallow. It answers "which is cheaper?" when the question that actually determines value is "which leaves me with something?".
Cheap expertise that walks out the door is expensive. Senior expertise that builds something you keep is the only version that compounds. Whichever route you choose, judge it by what remains when the person is gone, because talent is fragile, and systems are durable, and after nine months learning that the hard way, I know which one I'd pay for.
Whatever you choose, what will be left when they're gone?
Scale DNA installs the systems a senior hire or fractional executive would build, and leaves them in your business, owned by you. See where your biggest gaps are.