SAP ATP is not inventory

Core idea

Available-to-promise answers a commitment question: what quantity can the business responsibly promise to a customer, and when? It is not the same as asking what quantity exists physically in a plant or warehouse.

Inventory can exist and still be unavailable for a new promise. It may already be committed to another order, blocked for quality, reserved for production, held in the wrong location, or not considered by the relevant availability check configuration.

Why the distinction matters

Many support issues start with a simple mismatch: a user sees stock in one report, but the sales order confirms less than expected. The first reaction is often “ATP is wrong.” A better first question is: which supply and demand elements is the check allowed to consider for this material, plant, date, and document context?

The answer depends on master data, configuration, document type, timing, existing commitments, and sometimes product allocation or supply protection rules. The exact behavior is landscape-specific.

Practical diagnostic questions

• Is the stock physically available, unrestricted, and relevant for the plant or storage location being checked?
• Are existing sales orders, reservations, or dependent requirements already consuming the supply?
• Are purchase orders, production orders, or planned receipts included in the check scope?
• Is the requested delivery date before the next reliable receipt?
• Is a product allocation, supply protection, or special stock rule changing the result?

Support takeaway

Do not diagnose ATP from stock quantity alone. Diagnose it as a time-based promise calculation shaped by business commitments, supply reliability, and configuration. A useful ATP support note should include the material, plant, requested date, confirmed date, confirmed quantity, visible stock, open requirements, open receipts, and the document context that triggered the check.