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Key Takeaway
Inventory is where the gap between plan and reality shows up first. Closing it takes one demand number shared across functions, a supply plan linked to the financials, and a habit of comparing actuals with the plan while there's still time to act.
Every month, the S&OP meeting ends with an agreed plan. Demand, supply and finance have signed off. Everyone leaves aligned.
Three weeks later, a major customer changes an order, a supplier slips, and a promotion lands harder than expected. The warehouse is short on one product and overstocked on another. The plan hasn't changed. Reality has.
Inventory is the receipt for every planning assumption. When it's wrong, it's usually because the plan was wrong, or because nobody noticed it drifting.
Most S&OP processes don't fail in the meeting. They fail in the weeks after it. A few patterns come up again and again:
Different Functions, Different Numbers
Sales optimises for revenue, operations for cost and utilisation, finance for cash. When each works from its own version of demand, the "agreed" plan is really three plans with one label.
Spreadsheets Doing the Heavy Lifting
Separate files turn planning meetings into reconciliation sessions. By the time versions are matched, the numbers are already out of date.
Static Plans in a Moving Market
A plan approved as a snapshot has no way of warning you when it drifts. You find out when a customer calls or a warehouse fills up.
Firefighting Crowds Out Planning
When the team spends its days expediting shipments and fixing shortages, there's little time left to improve the plan that caused them.
Sources: a November 2025 survey of 164 S&OP and IBP professionals (81%), and a Gartner survey (42%), both as cited in a planning vendor's article. Secondary sources; treat as directional.
Plan vs. Reality Across the Chain
| Area | What the Plan Assumed | What Often Happens | How to Close the Gap |
|---|---|---|---|
| Demand | A single agreed forecast | Sales, operations and finance each work from their own view | One shared demand number that everything else links to |
| Supply | Reliable lead times and capacity | Delays and constraints appear mid-cycle | Review supply risk each cycle and update the plan, not just the schedule |
| Inventory | Stock levels that balance service and cost | Shortages in one place, excess in another | Targets set by product segment and reviewed as demand shifts |
| Finance | Budgeted working capital and margin | Cash tied up in stock, with the cost visible only at month-end | Supply plan and budget connected, so changes show up in the financials |
Work From One Demand Number
Link the supply plan, inventory targets and budget to a single demand figure. When demand changes, every downstream plan moves with it, instead of waiting to be rebuilt by hand.
Set Inventory Targets by Segment
Not every product deserves the same service level or the same safety stock. Group items by value, volatility and strategic importance, and set targets that reflect those differences.
Show the Financial Impact of Supply Decisions
A decision to build ahead or hold more stock has a working capital and margin cost. Putting that cost next to the operational choice helps operations and finance decide together.
Compare Actuals With the Plan Continuously
Display actuals alongside the plan and flag exceptions when they drift apart. Reviewing the few items that moved is far faster than re-checking everything, and it catches problems while they're still cheap to fix.
Run Scenarios Inside the Cycle
Ask what happens if demand rises 10%, a supplier is two weeks late, or a promotion overperforms, and see the effect on service levels, stock and cash before committing. Scenarios turn S&OP from a review of last month into a decision tool for next month.
Feed Execution Results Back Into the Plan
Track a short list of measures, such as forecast accuracy, service level and inventory levels, and feed the lessons into the next cycle. The plan only improves if what happened gets back to the people who made it.
The goal isn't a perfect forecast. It's a plan that adjusts quickly enough that reality never gets far ahead of it.
Begin with the basics: agree which demand number everyone uses, and put it in one shared place. Then pick one product family where shortages and excess are both visible, and compare plan with actuals every week for a quarter. The patterns you find will show where to invest next.
Keansa helps manufacturers and supply chain teams connect S&OP with financial planning: one shared demand view, supply and inventory plans linked to the budget, and scenario modelling that shows the cost of each option, so plans stay close to reality instead of drifting from it.
Want a plan that stays close to what's actually happening?
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