Why Does S&OP Fail? Five Reasons and How to Fix Them
S&OP fails for five reasons, and almost none of them are about software. The process gets owned by one function instead of the business, sales and finance work from different numbers, the meeting reports on the past instead of deciding about the future, there is no agreed baseline so nobody can prove whether it is working, and the executive layer does not turn up. Fix those five and a spreadsheet-based cycle will outperform an expensive platform run badly.
1. Is the process owned by supply chain alone?
This is the most common failure and the hardest to see from inside. When supply chain both runs the meeting and owns the outcome, S&OP quietly becomes a forecasting exercise. Sales treats the demand plan as somebody else's number, finance ignores it because it does not reconcile to the budget, and no decision that costs money gets made in the room. S&OP is a cross-functional decision forum or it is nothing.
2. Are sales, finance and operations working from one set of numbers?
If the sales forecast, the demand plan and the financial budget are three separate numbers maintained in three separate places, the monthly meeting gets spent reconciling them instead of deciding anything. One reconciled set of numbers, agreed before the meeting, is a precondition rather than a nice to have. That reconciliation work belongs in the week before, not in the room.
3. Does the meeting decide, or does it report?
A meeting that spends 45 minutes on last month's service level and 10 minutes on the next 12 months is a performance review, not a planning process. S&OP should look 3 to 18 months forward and end with decisions that someone is accountable for. If this week's stockouts keep hijacking the agenda, the problem is usually a missing weekly execution layer rather than a broken monthly cycle.
4. Is there an agreed baseline?
Without a baseline agreed at the start, you cannot demonstrate the process is working, and an initiative that cannot prove its value gets defunded inside a year. Fix the measures before the first cycle and record where they sit in month zero:
Forecast accuracy and forecast bias, measured at the level you actually plan
Inventory turns and total stock value
Service level or DIFOT against customer promise
Working capital tied up in inventory
5. Does the executive team actually attend?
When the executive sponsor starts sending a delegate, the meeting loses its decision rights within about two cycles. Attendance is the clearest single predictor of whether an S&OP process survives its first year. If the general manager will not commit an hour a month, do not start the process yet.
How long does it take before S&OP works?
A basic monthly cycle can be designed and piloted within 8 to 12 weeks. Maturing it into a process people trust usually takes two to three full cycles, so plan on roughly six months before the numbers are reliable enough to commit against. Businesses that abandon S&OP after one or two cycles almost always quit before the process has had a chance to work.
What does it look like when it works?
At Optus, Amit Asthana designed and implemented the S&OP framework across a devices business running an approximately A$1.5 billion P&L. Over two years the process released around $110 million in working capital through optimised inventory and demand planning, and recovered roughly $10 million a year in inventory value through new obsolete-stock clearance channels. The forum outlasted the programme and became the ongoing operational decision-making cadence.
What does fixing it cost?
Ongoing S&OP and IBP implementation with Supply Logis runs at around AU$5,000 per month. A fully loaded in-house demand planner in Australia costs AU$115,000 to AU$135,000 a year by comparison, but the two are not doing the same job: the consultant designs and embeds the cross-functional process, while the planner runs it day to day. We compare the two options in detail here.
If you are still deciding between S&OP and IBP, start with the difference between them.
Frequently asked questions
Why do most S&OP implementations fail?
Because they are run as a supply chain project rather than a business decision process. The five recurring causes are single-function ownership, unreconciled numbers, a backward-looking agenda, no agreed baseline, and absent executives.
Do we need software to fix a failing S&OP process?
Usually not. Many businesses run an effective monthly cycle on existing ERP and spreadsheet tooling. Software becomes the constraint later, once process discipline and cadence exist, not first.
Who should chair the S&OP meeting?
The executive who owns the P&L, typically the general manager or CEO. A process owner facilitates the cycle, but decision rights sit with the chair.
How long before we know it is working?
Design and pilot takes 8 to 12 weeks, then two to three full cycles before the numbers are trusted. Expect around six months before making major commitments against the plan.