The gap between allocated and billed hours, and how to catch it weekly.
This is the most expensive blind spot in professional services, and the reason it survives is that everything looks correct while it is happening.
Four engineers are allocated full time to a paying client. The resource plan is full. Utilization by allocation reads 100 percent. Nobody is idle on paper. And two of them spent their first eight working days waiting for client credentials, which is roughly 120 hours you paid for and cannot invoice.
Nothing on a standard resource view says so, because the allocation is real. The work is what did not happen.
Allocated hours minus billed hours, per person, per week.
Those two numbers are usually held in different places and rarely put side by side. Allocation lives in the resource plan, billed hours live in timesheets, and most firms compare them monthly, if at all. By then the money is gone and the explanation has been forgotten.
Weekly is the right cadence. The gap is recoverable as a client conversation while the week is still recent, and unrecoverable once it is three weeks old and nobody remembers which days were lost.
The causes repeat across firms and across industries, which is what makes them worth systematizing against:
None of these are your team underperforming. Every one is billable time that quietly became unbillable, usually for reasons on the client's side of the boundary.
Catching it is most of the value, because the fix is normally a conversation rather than a system change.
Raise it while it is happening. A client who hears on Wednesday that four engineers have been idle since Monday waiting on their IT department will usually either accept the invoice or unblock it fast. A client who hears about it in a month-end summary will do neither, and will reasonably ask why nobody said anything.
Do not allocate before access is confirmed. Week one is the most expensive week to get wrong, because that is when everyone is assigned and nobody can work.
Record the reason, not just the gap. Five engagements each losing a week to access delays is not five incidents. It is a broken onboarding process, and processes can be fixed in a way that individual incidents cannot.
On time and materials, this gap is straightforwardly lost revenue. The hours were available to bill and were not billed.
On fixed price, it is worse in a quieter way. You are not losing revenue, because the price is agreed. You are losing schedule. Days consumed with no scope delivered push the whole engagement toward the overrun where the real damage happens, and the budget burn against scope completion ratio will not look wrong yet, because you have not spent much either.
The mirror image is worth the same weekly look: people billing to an engagement they are not allocated to.
That usually means somebody is quietly helping out. It is often good for delivery and it is unbudgeted cost landing on an engagement whose margin was calculated without them.
A small gap is normal. Nobody bills every allocated hour, and a system that expected them to would be encouraging people to log fiction.
What matters is the pattern. A one-week gap at the start of an engagement that closes by week two is a normal ramp. A gap that persists past week three is a problem with a specific cause, and it will have a name: an access request, a decision, a person on the client side who has not replied.
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