Choose fractional support when the work is under roughly 20 hours a week and mostly scheduled. Choose full time when the work is reactive, spans several people, or requires someone inside your systems every day.
The instinct when you are overloaded is to hire full time immediately. That often overshoots. The better question is not how senior the support should be, it is how many hours of it you actually have, and how predictable those hours are.
Track a fortnight. Note every task you touch that does not need you specifically: scheduling, rescheduling, travel, expenses, chasing, formatting, data entry, calls you take because nobody else can.
Add it up. Under ten hours a week is comfortably fractional. Ten to twenty hours is fractional moving towards full time. Over twenty hours, or spread across two or three leaders, and you are already funding a full time role in lost output.
Both models need direction. Fractional support requires you to be organised about what goes across, because the hours are finite. Full time support requires enough delegated ownership to fill a week productively. Underloading a full time assistant is the most common and most expensive mistake.
The clean route is to begin fractional with the same assistant you would keep full time, then increase hours as more of the week moves across. That avoids the handover cost of changing person at exactly the point your dependency is growing.
Most people asking about fractional or full time are really asking something else: how much of my week can I hand over before the handover itself becomes the work. The honest answer depends less on your headcount than on how repeatable your admin is.
If your week is made of recognisable, recurring tasks, a fractional assistant can absorb a surprising amount of it. If it is unpredictable and reactive, you need presence rather than hours, and full time starts to earn its cost.
Track your own week for ten working days and tag every block as either work only you can do, work someone else could do with context, or work nobody should be doing. The second and third categories are your starting scope.
As a rule of thumb, two to three hours a day of delegable work supports a fractional arrangement comfortably. Beyond four, the switching cost of batching starts to outweigh the saving and full time becomes the cheaper option per hour returned.
The switch signal is rarely a feeling of being busy. It is a queue. If work is consistently waiting for your assistant's next day rather than waiting for your approval, you have outgrown the arrangement.
Scale in one step rather than several small ones. Add a day, hold it for a month, and check whether the queue clears. Moving from one day to full time overnight tends to create scope that has not been thought through, which is the fastest way to waste the extra cost.
Both mistakes are recoverable, but they are not equally expensive. Under-hiring costs you time and a certain amount of frustration: work waits, the backlog grows, and the leader quietly takes tasks back because it feels faster than waiting for the next available day. That is inefficient rather than dangerous, and it is visible within weeks.
Over-hiring is more corrosive because it hides. A full time assistant without enough scope will fill the week, usually with work of declining value, and both parties will feel vaguely dissatisfied without being able to name why. The cost is not only the salary but the sense that support did not work, which often delays hiring properly for another year.
The safer path is to start fractional with a clear scope, measure what actually gets handed over, and scale on evidence rather than intention. Two days a week with a defined remit and a documented process map gives you a much better basis for a full time decision than a hypothetical job description ever will.
It is also worth being explicit about the trigger for review. Set a date, usually eight to twelve weeks in, and agree in advance what would justify increasing days: a consistent queue, a second stakeholder relying on the same person, or automation work that keeps getting deferred because there is no time for it.
How many hours a month is a fractional executive assistant? Typically from a few days a month up to around two or three days a week, scaling as more work moves across.
Can I start fractional and move to full time later? Yes, and it is the most common path. Keeping the same assistant through the transition avoids a second onboarding.
Is fractional support shared with other clients? A fractional assistant supports a small number of clients with committed, scheduled hours rather than being pooled across a queue.
More insights | Alvara Partners