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

The S&OP process runs the same five steps every month, in order: data gathering, demand review, supply review, pre-S&OP reconciliation, and executive sign-off. Sales and operations planning isn't a meeting — it's a cycle that ends each month with one agreed plan that sales, operations, and finance all commit to. The discipline is running the steps in sequence so that by the time leadership sits down, the only thing left is the decision.

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, every month, without skipping the hard one. Here's each step, what happens in it, and the operator detail that makes or breaks it.

Where the five steps come from

The five-step monthly cycle isn't a framework somebody invented last year. The term S&OP and its modern structure trace to the early 1980s and consultant Richard Ling at Oliver Wight, who built it to balance supply and demand over a one-to-twelve-month horizon (Wikipedia, 2024).

The professional body that owns the definition today is ASCM, formerly APICS. It defines S&OP as the function of setting the overall level of manufacturing output to best satisfy planned sales while meeting business objectives like profitability and customer lead times (ASCM, 2024).

If you want the deeper background on what S&OP is and why it matters, start with our guide on what S&OP is. This article assumes you know the why and focuses on the how — running the monthly cycle so it actually produces a decision.

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. Use MAPE on the movers and bias on everything. The Institute of Business Forecasting documents both as standard demand-planning metrics for exactly this reason (IBF, 2023). If you're not tracking whether you ran high or low, you re-absorb the same mistake every month.
• Reconcile to one source. Sales pulls 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. McKinsey ranks improving information flows between teams as the first of five design best practices for operations planning (McKinsey, 2023). Live pipelines from ERP and POS turn a two-week scramble 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. The order matters: baseline first, judgment second.

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. Collect it 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. That feedback loop is the whole point — for the tactics that move the number, see how to improve forecast accuracy.

Step 3: Supply review

Operations takes that demand number and stress-tests it against reality. Can we actually make it? The output isn't yes or no. It's a supply plan with the constraints named and the cost of resolving each one priced.

Check	What you're answering	The trap
Capacity	Does demand fit available hours, lines, labor?	Treating one bottleneck as a total "no"
Inventory position	What's on hand, in transit, committed?	Ignoring stranded stock that's already paid for
Lead-time / supplier	Long-lead parts, single-source risk, supplier caps	Discovering it the week you need the part
Constrained vs unconstrained gap	Market demand minus what you can supply	Hiding the gap instead of pricing it

That last row is the one that matters. The gap between what the market wants and what you can supply is the entire reason the next step exists. Price the fixes — overtime, a second shift, expedited freight, a capacity investment — so leadership can weigh them.

This is also where excess inventory gets created or avoided. Gartner notes that overproduction driven by fixed-cost absorption ties up working capital and breeds obsolescence (Gartner, 2022). The supply review is where you catch that before it ships.

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. The financial translation here is the bridge to FP&A; we cover that handoff in detail in connecting S&OP to financial planning.

Step 5: Executive S&OP

Leadership reviews the reconciled plan, decides the trade-offs pre-S&OP couldn't, and commits. One number, owned. ASCM frames this stage exactly that way: executives review the plans and recommendations from pre-S&OP to develop a final plan to be acted on (ASCM, 2024).

• 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. If you want a ready-made structure, our S&OP meeting agenda template lays out the roles and timeboxes.

The cadence that makes it work

Step	Owner	Timing in cycle	Common failure
1. Data gathering	Planning / analytics	Days 1–3	Manual exports, two weeks lost
2. Demand review	Demand planning	Days 4–7	Overrides with no reasons
3. Supply review	Operations	Days 8–11	"Can't do it" with no cost attached
4. Pre-S&OP	Cross-functional	Days 12–15	Skipped — gaps pushed to executives
5. Executive S&OP	Leadership	Days 16–18	Re-litigating the forecast

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.

The payoff is real, and it compounds. McKinsey reports that optimized operations planning can lift supply chain throughput 10–15% with no change in assets, and cut costs 5–10% over the longer term (McKinsey, 2023).

How this maps to maturity

Most companies don't run all five steps cleanly on day one, and that's expected. Gartner's five-stage S&OP maturity model — react, anticipate, integrate, collaborate, orchestrate — puts most organizations at stages 1 to 3, where strategic and operational planning still don't connect (Gartner, 2021).

The five steps are the integrate stage made concrete. You move up the ladder by adding the harder steps in order. First a real demand number instead of last-year-plus-5%. Then a priced supply plan instead of a flat "no." Then pre-S&OP instead of dumping gaps on executives.

AI raises the ceiling on each step but doesn't replace the cadence. McKinsey's work on machine-learning supply-chain planning shows the gains come from better forecasts and faster scenario analysis feeding the same decision rhythm, not from removing the human decision (McKinsey, 2021).

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. For the habits that separate strong cycles from weak ones, see our S&OP best practices guide.

Frequently asked questions

What are the 5 steps of the S&OP process?

The five steps are data gathering and review, demand review, supply review, pre-S&OP reconciliation, and the executive S&OP meeting. They run in that order every month, ending with one agreed plan that sales, operations, and finance all commit to. The sequence matters because each step feeds the next — skipping pre-S&OP, for example, pushes unresolved gaps onto executives who then can't decide.

How long does the S&OP cycle take?

A typical monthly cycle runs about three weeks from data gathering to executive sign-off. Data and demand work fills the first one to two weeks, supply review and pre-S&OP fill the middle, and the executive meeting itself runs 60 to 90 minutes near the end. The key is keeping the same cadence every month so the rhythm becomes routine rather than a scramble.

What's the difference between pre-S&OP and the executive S&OP meeting?

Pre-S&OP is a working session where demand, supply, and finance leads close most gaps and frame the genuine trade-offs that remain. The executive S&OP meeting is where leadership decides those framed trade-offs and commits to one plan. Done right, 90% of the work happens in pre-S&OP, so the executive meeting is a sign-off rather than a debate.

Why do S&OP processes fail?

The most common failure is skipping pre-S&OP, which dumps unresolved gaps on executives and turns the meeting into an argument. Other frequent causes are dirty data that forces teams to spend the cycle agreeing on numbers, never measuring forecast accuracy, and letting the monthly cadence slip under pressure. Fixing data integration and protecting the cadence resolves most of these before the steps themselves matter.

Do I need software to run S&OP?

No — you can run a disciplined five-step cycle in spreadsheets, and plenty of mid-market manufacturers do at first. Software helps most when manual data gathering eats two weeks of the cycle or when forecast and scenario analysis outgrow what a spreadsheet can hold. The process discipline comes first; the tooling earns its place once the cadence is solid and the data bottleneck is the binding constraint.

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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.