Inventory and costing in SAP S/4HANA

Across the last two stations stock moved in both directions, and one number passed through both without ever being discussed: what was a single unit valued at?

That number is not an accounting detail. It decides the profit you declare at month end — and one item bought at different prices can produce two entirely different profit figures depending on the method, with both of them correct.

The two methods, and the difference is not technical

	Standard cost	Moving average
Unit value in the books	Fixed, set in advance and reviewed periodically	Changes with every receipt
Where does a purchase price difference go?	To a separate difference account	Absorbed into the stock value
What you see in the report	The variance from plan, stated openly	A real cost, with no visible variance
Suits	Manufactured items, and stable repeat items	Bought-in items, and volatile prices
The question it answers	“How far did we deviate from plan?”	“What did it actually cost us?”

The last row is everything. Choosing between the two is not an accountant’s choice; it is a choice of which question you want your monthly report to answer.

A factory that manages cost against a plan and holds its managers to the variance wants standard cost, because it shows the variance instead of swallowing it. A distributor whose suppliers’ prices move weekly wants moving average, because a variance that appears every day is not information, it is noise.

The price difference account — why its existence is a feature

Under standard cost, buying above the standard does not raise the stock value. The difference drops into a separate account.

That has a consequence worth reading twice: the balance of that account at month end is a measure of purchasing performance against plan, with no further analysis and no spreadsheet beside it.

The common error is treating it as a rubbish account whose balance is carried out at year end with no questions asked. It is in fact the cleanest performance report you own — a swollen balance means either that purchasing is buying above plan, or that the standard cost itself has not been reviewed since the market moved. Both readings are a management decision waiting for its owner.

The practical rule for choosing

Ask about the item, not about the company. The method is chosen per item, and anyone imposing one on everything “for consistency” loses information on half their catalogue.

The quick rule:

• Price stable and manufactured in house? Standard cost, because the variance is the information.
• Price volatile and bought in finished? Moving average, because reality is the information.
• Do not know? Start with moving average, because it demands no reliable cost plan — and a standard cost with no periodic review is worse than none, since it produces a variance measuring the age of the number rather than the performance of purchasing.

Counting — where the books meet the shelf

The rule is blunt and it holds in any system: a count difference is not a system error until proven otherwise; it is a procedure error.

Three causes produce most of them: a movement that happened on the shelf and was never recorded, a unit of measure mixed between receipt and issue, and a return that entered the warehouse with no document. All three are fixed by procedure, not by a book adjustment.

An adjustment is posted as an entry, and a reason is written for it. An adjustment with no written reason is the concealment of a problem that will recur next month at the same figure.

The inventory cycle explained independently of any product — the movements, the valuation methods and their effect on profit — is in the inventory and costing cycle.

What you actually do at this station

This exercise is the most useful thing at this station, and it can be done by hand if you have no environment:

1. Take one item and set its standard cost at 10 before you begin.
2. Buy 100 units at 10, then 100 units at 14.
3. Sell 150 units.
4. Calculate cost of sales and closing stock value under both methods, and under standard cost, the balance of the price difference account.
5. Write the difference as a figure, then state which number reaches the income statement under each method.
6. Write one line explaining why the two numbers differ and why both are correct.

Anyone who runs this exercise by hand once never forgets the difference and never needs to memorise it. Anyone who only reads about it confuses the two methods in their first meeting.

The three commonest errors

One: a standard cost that is never reviewed. A number set two years ago makes the difference account measure the staleness of the number rather than the variance of performance. Periodic review is part of the method, not an addition to it.

Two: a count adjustment with no reason. It cleans the balance and leaves the cause, so the difference returns.

Three: reading a profit figure without knowing the method. Two managers read the same report and disagree about it because one of them does not know how the goods were valued. Presenting a profit figure without naming the valuation method is presenting half an item of information.

What these choices do to project complexity and to the number of consultant-days they consume is set out in the SAP S/4HANA guide.

The acceptance test for this station

1. Run the 100-and-100-and-150 exercise and write down all four figures.
2. Choose a method for three different items with a written reason for each.
3. Explain the price difference account in three lines, and what a swollen balance means.
4. Write a five-step counting procedure that prevents the commonest differences.
5. Explain to a non-financial manager why profit changes when the method changes and the sale does not.

What comes next

The figures are right at the level of the movement. The next station gathers them into a statement: the close and the reports — containing the idea this whole generation was built for, the universal journal, and why an entire job that occupied the closing team every month disappeared with it.