Why Negative Projected Balance and ATP Are Information in EDGEBIC

In EDGEBIC by User Solutions a negative projected balance or a negative available-to-promise is information, not an error: a below-zero number means committed demand exceeds projected supply, and the plan surfaces it, with the exact bucket and amount, so you can resolve the shortfall rather than being blocked from a legitimate order. Committed demand ahead of supply is intentional planning debt, and the calendar's job is to show you that debt clearly, not to pretend it away.

This post explains what below-zero numbers mean, why EDGEBIC shows them instead of stopping you, and how to close the gap. For the balance itself, see reading a projected available balance row by row, and for the wider loop start from the EDGEBIC planning guide.

Below Zero Is a Real Condition

The projected available balance walks forward bucket by bucket, adding supply and subtracting demand. When demand outpaces supply, the balance can fall through zero. EDGEBIC lets it, because a negative balance describes something real: in that bucket, committed demand exceeds projected supply.

That is not a calculation failure. It is a fact about your plan. You have promises to keep that your current supply does not cover in that window. The number is the size of the gap, and the bucket is where it bites. Both are exactly what you need to fix it.

The same is true of available-to-promise. A negative discrete value at a supply point means firm demand between that point and the next exceeds the supply arriving there. A negative cumulative value means your total position across the horizon is underwater. Neither blocks anything. Both name an overcommitment.

Why the Plan Does Not Block You

It would be easy to build a plan that refuses to go negative, clamping every balance at zero. EDGEBIC does not, and the reason is practical.

Committed demand ahead of supply is often deliberate. You take a real order knowing supply is tight, planning to expedite a build or pull in a purchase to cover it. That is normal planning debt, not a mistake. A plan that hard-blocked the order, or hid the shortfall by refusing to show a negative, would rob you of the information you took the order on purpose to manage.

So EDGEBIC surfaces the below-zero number instead. It trusts you to act on honest information. The negative balance is not the system saying you did something wrong; it is the system saying here is the gap, in this bucket, this large, go close it.

A Worked Example: A 40-Unit Gap in Week 6

Say a part's projected balance walks down cleanly for five weeks and then reads negative 40 in week 6. Nothing errored. What does it mean and what do you do.

It means that by week 6, committed demand exceeds projected supply by 40 units. You are 40 short in that bucket, given everything currently planned. The calendar has already done the hard part: it named the bucket and the amount.

You have two levers. Add supply: firm a replenishment sized to cover the shortfall and timed to land in or before week 6. Once it exists as real incoming supply, the netting adds it to the balance from its arrival bucket forward, and week 6 climbs back above zero. Or reduce demand: move or cancel a firm order that is driving the gap, if the customer situation allows. Either way you are covering a known 40-unit shortfall with a specific action, not guessing.

The below-zero number turned a vague worry into a concrete task.

Local Versus Horizon-Wide Shortfalls

Not all negatives are equal, and the two ATP values help you tell them apart.

A single negative discrete ATP is local: an overcommitment between two supply events that a later receipt may cover. Watch the cumulative column; if it recovers at a later supply point, the local dip is handled downstream.

A cumulative ATP that goes negative and stays negative is broader: your total commitments across the horizon exceed your total supply, and no later receipt rescues it. That is over-promising at the horizon level.

Read the cumulative column to judge scope. A persistent negative cumulative means promises exist that current supply cannot keep, and it deserves priority.

Reading Negatives as a To-Do List

The healthy way to read below-zero numbers is as a to-do list, not an alarm. Each negative bucket is a task: a known amount to cover, in a known window, by adding supply or moving demand. The plan has already located the problem for you, which is the expensive part.

The failure mode is the opposite: treating a negative as an error, ignoring it, and letting the planning debt run until it becomes a missed ship date. The number exists precisely so that does not happen. Resolve the negatives while they are still forecasts, and they never become surprises.

For how the two promise columns produce these values, read ATP discrete vs cumulative, reading the two promise columns, and for how a firmed order closes the gap, read why a replenishment suggestion does not lift projected balance until you firm it. For how a shortfall surfaces ahead of time, read how a stockout shows up before it happens.