The S&OP Process: 5 Steps in the Monthly Cycle

The S&OP process steps are the same five every month, and the discipline is running them in order without skipping the one that's hard. Sales and operations planning isn't a meeting — it's a cycle: data gathering, demand review, supply review, pre-S&OP reconciliation, and executive sign-off. I ran this at a $250M furniture manufacturer, and the version that worked looked nothing like the version we started with. Early on, we'd jump straight to the executive meeting with three conflicting spreadsheets and spend 90 minutes arguing about whose numbers were right. Nothing got decided. The fix wasn't a better meeting. It was running the five steps in sequence, so by the time leadership sat down, the only thing left was the actual decision. Here's each step, what happens in it, and the operator detail that makes or breaks it.

Step 1: Data gathering and review

Before anyone forecasts anything, you close the books on last cycle. Pull the actuals: sales, shipments, on-hand inventory, open orders, and — the one most teams skip — last month's forecast accuracy.

• Measure forecast error by SKU and family. MAPE on the movers, bias on everything. If you're not tracking whether you ran high or low, you re-absorb the same mistake every month.
• Reconcile to one source. Sales pulling from CRM, ops from the ERP, finance from the GL — three systems, three truths. Pick the system of record and make everyone read off it.
• Flag the exceptions. You don't review 8,000 SKUs. You review the ones that moved: big misses, demand swings, the items driving 80% of the variance.

The operator tell: if this step takes your team two weeks of manual exports, the data isn't integrated and the rest of the cycle starts late and stressed. Live pipelines from ERP and POS turn this into a same-day step.

Step 2: Demand review

Now the demand team builds the unconstrained forecast — what the market wants, before worrying about whether you can make it.

1. Start with the statistical baseline. A model run off clean history, by SKU and family. Not last-year-plus-X in a spreadsheet — an actual forecast you can measure.
2. Layer structured market input. Sales and marketing add what the model can't see: promos, launches, lost or won accounts, known seasonality shifts. Collected in writing, with reasons, so you can audit the assumptions later.
3. Adjust for known bias. If a sales region runs 25% high every cycle, apply the haircut. Bias you've measured is bias you can correct.
4. Output one demand number with the assumptions attached.

The discipline here is separating the baseline from the overrides. When sales pushes a number 40% above the statistical forecast, that override should be a line item with a name and a reason on it — not silently baked in. Next month you check whether the override was right, and the person who made it learns.

Step 3: Supply review

Operations takes that demand number and stress-tests it against reality. Can we actually make it?

• Capacity check — does demand fit available production hours, lines, and labor? Where do we hit a constraint?
• Inventory position — what's on hand, in transit, and committed? Where are we long, where are we short?
• Lead-time and supplier constraints — long-lead components, single-source risk, supplier capacity limits.
• Constrained vs unconstrained gap — the difference between what the market wants and what you can supply. This gap is the whole reason the next step exists.

The output isn't "yes we can" or "no we can't." It's a supply plan with the constraints named and the cost of resolving each one priced — overtime, a second shift, expedited freight, a capacity investment.

Step 4: Pre-S&OP (reconciliation)

This is the step everyone wants to skip and the one that decides whether S&OP works. Demand, supply, and finance sit in a working session and close the gaps before leadership ever sees the plan.

• Resolve what can be resolved at the working level. Most gaps don't need an executive. The demand and supply leads can settle them with the numbers in front of them.
• Package the genuine trade-offs. The decisions that need authority — invest in capacity or cap demand, hold inventory or risk the stockout, take the margin hit or push the lead time — get framed as clear options with dollar figures and a recommendation.
• Tie it to finance. Translate the volume plan into revenue, margin, and cash. If the plan doesn't reconcile to the financial picture, you find out here, not at quarter-end.

Done right, pre-S&OP is where 90% of the work happens. The executive meeting becomes a sign-off, not a debate. Skip this step and you've recreated the three-conflicting-spreadsheets disaster — leadership reconciling data live, which is the most expensive way possible to do arithmetic.

Step 5: Executive S&OP

Leadership reviews the reconciled plan, decides the trade-offs pre-S&OP couldn't, and commits. One number, owned.

• Decide, don't re-litigate. If the meeting reopens the demand forecast from scratch, steps 1-4 failed. Executives decide the framed trade-offs; they don't rebuild the plan.
• Commit publicly. The agreed number becomes the number — sales sells to it, ops builds to it, finance budgets to it. No private side-forecasts.
• Assign the actions. Capacity decisions, inventory moves, markdown triggers — each with an owner and a date.

The meeting should run 60-90 minutes and end with decisions, not another round of analysis.

The cadence that makes it work

The whole cycle lands in roughly three weeks and repeats every month. Two rules keep it honest: same cadence every month — the discipline is in the rhythm, not the heroics — and measure last cycle's accuracy first, so the process improves instead of repeating its mistakes.

Where most teams break

In order of how often I've seen it:

1. No pre-S&OP. Gaps get dumped on executives, the meeting becomes a brawl, nothing gets decided.
2. Dirty data. Half the cycle is spent agreeing what the numbers are. That's a data-integration problem wearing an S&OP costume.
3. Forecast accuracy never measured. Same errors, every month, forever.
4. No real demand number. "Last year plus 5%" isn't a forecast — it's a wish with a percent sign.
5. Cadence slips. Skip a month under pressure and the discipline never comes back.

Fix the cadence and the data first. The rest of the steps only work when those two are solid.

Want to see where your cycle breaks? Send me read-only access to your current S&OP process — or a sample plan — and I'll run a free planning-maturity and stranded-inventory teardown: which of the five steps is failing, your real forecast accuracy, and where the trapped cash is hiding. You keep the analysis either way. Book a free teardown and we'll find the broken step before next cycle.