How to Implement a Sales & Operations Planning (S&OP) Process

What S&OP actually is

Sales & Operations Planning (S&OP) is a monthly cross-functional process that aligns demand, supply and finance around a single operating plan. It is not a forecast, a spreadsheet, or a meeting. It is the mechanism by which a leadership team makes a small number of consequential decisions each month — about capacity, inventory, pricing, hiring and priorities — with the same numbers in front of them.

Companies typically arrive at S&OP for one of three reasons: revenue has outgrown the informal way decisions used to get made; margins have started slipping without a clear cause; or the leadership team is spending its time on operational firefighting instead of strategy. In each case, the underlying issue is the same — the business no longer has one shared view of the near-term future.

The five steps of a monthly S&OP cycle

A mature S&OP cycle is sequential. Each step produces an artefact that the next step depends on. Skipping a step, or running them in parallel to save time, is the most common reason implementations fail.

1. Product review

The cycle starts with product: what is being launched, transitioned, or phased out in the planning horizon. New products distort forecasts and consume capacity out of proportion to their revenue; discontinued lines free up capacity but often continue to be planned by habit. The product review makes those decisions explicit and time-bounded.

2. Demand review

The demand review produces a single, unconstrained forecast by product family — what the business would sell if supply were not a constraint. Sales, marketing and product own it jointly. The output is a number, a set of assumptions, and a documented change from last month with a stated cause. Anonymous, unreviewed forecasts have no place here.

3. Supply review

The supply review takes the demand plan and asks a plain question: can we deliver it, and at what cost? Constraints — capacity, lead time, inventory, labour — are surfaced, and the supply team returns with options. The point is not to match demand exactly. The point is to make the trade-offs visible before the leadership team is asked to decide.

4. Financial reconciliation

Volume becomes revenue, revenue becomes margin, and margin becomes cash. Finance converts the operating plan into a financial view and compares it to the business plan the board signed off on. Any gap — up or down — is quantified and attributed to a driver. If finance cannot tell you why the plan differs from the budget, the cycle is not ready for step five.

5. Executive review

The executive S&OP meeting is where decisions are made. It is not a status update. Leadership receives a reconciled plan, a short list of decisions required, and the risks attached to each option. Ninety minutes is usually enough. Decisions are recorded, dated, and become the input to next month's cycle.

Roles and accountabilities

A working S&OP process has five named owners. Nothing else needs to be added, and nothing should be removed.

• S&OP lead — owns the cadence, the artefacts and the outcome of the cycle. Usually a senior operations or planning leader.
• Demand owner — signs off the demand plan. Typically the commercial or revenue leader.
• Supply owner — signs off the supply plan. Operations, manufacturing or fulfilment leader.
• Finance partner — owns the reconciliation and the financial view. Usually FP&A.
• Executive sponsor — chairs the executive review and holds the process to its purpose. CEO or COO in most companies.

KPIs that indicate the process is working

S&OP is not measured by whether the meetings happen. It is measured by whether the business gets better at forecasting itself and at meeting the plan it commits to. Four KPIs are enough:

• Forecast accuracy at the product-family level, one and three months out.
• Plan attainment — units and revenue delivered versus the plan committed in the executive review.
• On-time-in-full (OTIF) service level against the demand plan.
• Days of inventory against target, by category.

Report these four every month, in the same format, on the same page. Trends matter more than absolutes.

Common failure modes

Most S&OP implementations that stall do so for one of the following reasons.

• No decision rights. The executive review becomes a review of numbers with no authority to change them.
• Forecast by consensus. The demand number is negotiated down to be safe, not signed off as a real view.
• Finance runs late. Reconciliation lags a month behind the operating plan, so the executive review is looking at yesterday.
• Too much tooling, too early. A planning system is bought before the process is stable, and configuration replaces discipline.
• No memory. Last month's decisions are not tracked, so the same trade-offs are re-argued each cycle.

A 90-day rollout

The rollout below is what we typically use with a company between roughly $10m and $500m in revenue. It compresses if the business is smaller and lengthens if the product hierarchy is genuinely complex, but the shape is the same.

Days 1–30: diagnose and design

Interview the demand, supply, finance and executive owners. Map the current planning flow — where numbers come from, who signs them, how they are used. Define the product-family hierarchy, the cadence and the artefacts. Confirm the executive sponsor and the five owners. Produce a one-page process design that the executive team signs off.

Days 31–60: dry-run one full cycle

Run every step end-to-end, using existing tools — spreadsheets are fine at this stage. The objective is not to produce a perfect plan; it is to produce every artefact, on time, with the right owner. Debrief each step. Fix the artefact templates and the timing of the handoffs. Do not change roles.

Days 61–90: run the first real cycle

The second cycle is the first the executive team treats as binding. Decisions taken in the executive review become the operating plan for the following month. Publish the four KPIs. Book the next three cycles in the leadership calendar. From this point on, the process owns itself.

When to bring in outside help

Companies often try to implement S&OP purely internally, and a few succeed. The two conditions that make outside help worthwhile are the same two conditions that make it wasteful without: the leadership team must have decided that S&OP is the operating model going forward, and it must be willing to sign off the design before the first cycle. Without both, the process reverts to whatever preceded it within a quarter.

Momentum IM sets up S&OP as an operational implementation engagement, not an advisory one. We design the process with the executive team, run the dry-run cycle alongside the internal owners, and hand over a working cadence — with the four KPIs, the meeting artefacts, and a documented owner for each step. Typical engagement horizon is 90 days.