There are two types of availability check.
- Static availability check:
Availability check of the stock types in inventory management
- Dynamic availability check:
Check of available stocks from the viewpoint of material requirements planning
Availability Check of the Stock Types (Static Availability Check)
For every material movement, the system automatically performs an availability check of the stock types. This availability check prevents the book inventory balance of the various physical stock types (for example, unrestricted-use stock) from becoming negative. With this type of availability check, only the stocks available at the time of entry are taken into account. This check is carried out automatically, and no settings can be made for it in the system.
The static availability check covers the relevant stock affected at plant, storage location, and special stock level. The stocks affected are determined via the movement type. Nonavailability leads to an error message.
For example, you enter a transfer posting for a material with movement type 321, transferring 20 pieces from stock in quality inspection to unrestricted-use stock. The system then checks whether 20 pieces of the material actually exist in stock in quality inspection at the specified plant and storage location.
Check of available stocks from the viewpoint of material requirements planning (Dynamic Availability Check)
In addition to checking the stocks that physically exist in the warehouse, available stock can also be checked from the viewpoint of Material Requirements Planning. With the dynamic availability check, planned receipts and issues can also be taken into account. This check enables you to prevent an already reserved quantity from being withdrawn or reserved for another purpose, for example.

For example, today there are 100 pieces of a material in unrestricted-use stock in the warehouse. Thirty pieces of the material are reserved for withdrawal tomorrow, and another 20 pieces are reserved for withdrawal the day after. Consequently, only 50 pieces of the material are available today, because the rest have already been reserved for other purposes. If you tried withdrawing 60 pieces today, the system would display a warning or error message, depending on the configuration.
This type of availability check is used in several applications, for example, in:
- Inventory Management when creating a reservation or entering a goods issue
- Sales and Distribution when creating a sales order
- Production when creating a production order
- Purchasing when creating a stock transport order

