Acquiring a Basic Understanding of Available-to-Promise (ATP)

The availability check for sales documents and deliveries is basically carried out at plant/storage location level, if the storage location check is not deactivated in Customizing.

In sales documents, the availability check takes place in the plant of the order item. The plant is usually determined automatically by plant determination based on master data. The possible master data in which the delivering plant can be defined is prioritized as follows:

1. Customer-Material Info Record
2. Customer Master Record of the Ship-To Party of the Item
3. Material Master Record

However, the plant of the order item can also be specified manually during processing.

If the material is not available in the original plant, the plant in the order item can be replaced manually by another plant, if Advanced Available-to-Promise (aATP) is deactivated. If Advanced Available-to-Promise (aATP) is activated, the plant of the order item can be replaced automatically as part of Alternative-Based Confirmation (ABC) by one or more plants. Shipping then takes place from this plant(s).

In the solution Available-to-Promise, automatic determination of the storage location is not possible in sales documents. The availability check of the sales documents is therefore only storage-location-specific if a storage location is specified for the document item manually or by system adjustment.

In the business function Advanced Available-to-Promise (aATP), as part of Alternative-Based Confirmation (ABC), the storage location can be determined automatically for the order item. The availability is then checked in this plant/storage location combination. If the material is not available in the storage location, it can be replaced by another storage location or by another storage locations with cumulative ATP quantity. The selection of the storage location can be defined in the Manage Substitutions - Locations app, and influenced by the alternative determination of the substitution strategy.

Outbound delivery items usually have a storage location in addition to the plant. The availability check then always takes place at the delivering plant and storage location level of the delivery item, except if the availability check at storage location level is deactivated. The storage location is usually determined automatically in deliveries.

Depending on the characteristics of the requirement (plant, plant/storage location), the availability check is carried out at different levels. For example, if a requirement only refers to a plant, the check is only carried out at plant level. However, if the requirement refers to a storage location, the system must also check for the storage location. The level with the lowest cumulative ATP quantity determines the result.

The availability check in the order is usually preceded by shipment and transportation scheduling. If Advanced Available-to-Promise (aATP) is activated, if applicable, by Business Process Scheduling (BPS), scheduling determines various dates. From the point of view of the availability check, the material availability date is decisive.

If scheduling is activated, the material availability date is first determined through backward scheduling, starting from the requested delivery date. The availability check refers to the material availability date. This is the requirement date. The material had to be available on the material availability date, because only then can the shipping process start. If the material availability date is today, that is, the same as the order entry date or in the future, and the material is available on the material availability date, the requested delivery date can be confirmed. A schedule line is generated for the sales document item and the requested quantity and date are confirmed.

If the material availability date calculated by backward scheduling is in the past or if the material is not available on the material availability date, the requested delivery date cannot be confirmed. SAP S/4HANA then tries to determine the next possible delivery date(s) using forward scheduling. The earliest point in time at which the material is available, is the or is a material availability date. This is the starting point for forward scheduling to propose the or a possible delivery date.

If scheduling for the sales document is deactivated, the requested delivery date corresponds to the material availability date.

The Available-to-Promise (ATP) check is successful if there is sufficient cumulative ATP quantity for the material, on the material availability date, in the plant or plant/storage location of the item.

The basic check logic of the ATP check is hard-coded and cannot be changed in Customizing. Starting from the material availability date of the order item into the past, the system checks whether there are stocks or receipts with sufficient ATP quantities. If yes, the order item is confirmed as requested and the material is reserved for this order item. As a result, the confirmed quantity reduces the ATP quantity of the stocks or receipts against which it was confirmed. Sales orders can only reduce ATP quantities whose date lies before the material availability date. The ATP quantities of the stocks and receipts are totaled during each check to calculate a cumulative ATP quantity. This means that if there is sufficient cumulative ATP quantity on the material availability date, the requirement is confirmed. If this is not the case, the system checks whether cumulative ATP quantity exists from the material availability date into the future and, if yes, creates one or more delivery proposals. Since confirmed requirements reduce the cumulative ATP quantity, the material is reserved for the requirement. Which stocks, receipts, and requirements are considered in the calculation of the cumulative ATP quantity is defined in Customizing of the scope of check.

The check logic is illustrated in the following example.

For material T-ATP100, there are 80 pieces of unrestricted-use stock and 20 pieces of stock in quality inspection in plant 1010, storage location 101A. Unrestricted-use stock is always taken into account when calculating the cumulative ATP quantity. Quality inspection stock is only taken into account if it is defined in Customizing which, in this example, it is not. This means that unrestricted-use stock accounts for 80 pieces of the ATP quantity in the calculation of the cumulative ATP quantity. Stock always refers to today and therefore, in plant 1010 and plant/storage location 1010/101A, the cumulative ATP quantity from today to all eternity is 80 pieces.

A purchase order has been entered in the system for 60 pieces of material T-ATP100, with a delivery date of 30.06.2023, for plant 1010, and storage location 101A.

In addition, there is a second purchase order item for 40 pieces of material T-ATP100, with a delivery date of 31.07.2023, for plant 1010, without specifying a storage location.

As it has been defined in Customizing that purchase orders are included in the calculation of the cumulative ATP quantity, and the storage location check is not deactivated, the following situation arises for material T-ATP100 in plant 1010:

• Cumulative ATP quantity starting from today until the delivery date of the first purchase order item (30.06.2023): 80 pieces.

• Cumulative ATP quantity starting from the delivery date of the first purchase order item (30.06.2023) up to the delivery date of the second purchase order item (31.07.2023): 140 pieces.

• Cumulative ATP quantity starting from the delivery date of the second purchase order item (31.07.2023) onwards into the future: 180 pieces.

The situation for material T-ATP100, in plant 1010, for storage location 101A is as follows:

• Cumulative ATP quantity starting from today until the delivery date of the first purchase order item (30.06.2023): 80 pieces.

• Cumulative ATP quantity starting from the delivery date of the first purchase order item (30.06.2023) onwards into the future: 140 pieces.

A sales order is entered in this initial situation for 70 pieces of material T-ATP100, with a requested delivery date of 13.07.2023. Backward scheduling calculates the material availability date (= requirement date) of 10.07.2023 and the requested delivering plant is 1010. The sales order item does not contain a storage location. This means that availability can only be checked at plant level.

On 10.07.2023, the cumulative ATP quantity in plant 1010 is 140 pieces, so the sales order requirement of 70 pieces can be confirmed as requested. The availability check in the order item is successful and therefore runs invisibly for the user. The result is a schedule line confirmed as requested for the sales order item.

Since the delivery of the item takes place in the future, the confirmed quantity of 70 pieces must be "reserved" for this sales order item. This is achieved by reducing the cumulative ATP quantity by the confirmed quantity. However, this assumes that the sales document is taken into account (that is, deducted) when calculating the cumulative ATP quantity. This is defined in Customizing in this scenario. Requirements always reduce the ATP quantity of the stock or receipts that are the closest to them when looking into the past. However, the ATP quantities of the stock and receipts are only reduced after the order has been saved (see the figure "Situation After Saving the Sales Order").

As a result, the next requirement has less cumulative ATP quantity available for confirmation. However, this also means that the cumulative ATP quantity is distributed according to the first come, first served principle.

After saving the sales order, the cumulative ATP quantity for material T-ATP100 in plant 1010 is as follows:

• Cumulative ATP quantity starting from today until the delivery date of the second purchase order item (31.07.2023): 70 pieces.

  The unrestricted-use stock now delivers only 70 pieces of the ATP quantity. The purchase order item of the first purchase order no longer delivers an ATP quantity, since requirements always reduce the ATP quantity of the stock or receipts that are closest to them when looking into the past.

• Cumulative ATP quantity starting from the delivery date of the second purchase order item (31.07.2023) onwards into the future: 110 pieces.

The situation for material T-ATP100, in plant 1010, in storage location 101A is as follows:

• Cumulative ATP quantity starting from today until the delivery date of the first purchase order item (30.06.2023): 80 pieces.

• Cumulative ATP quantity starting from the delivery date of the first purchase order item (30.06.2023) onwards into the future: 140 pieces.

The availability check can also be carried out using the replenishment lead time of a material.

The Monitor Stock/Requirements List app shows the current stock/requirements situation for a certain material. It shows available quantities, but not the cumulative ATP quantity. It should therefore not be used to determine availability of the material for a new requirements element.

The Stock: Single Material app shows the current stock level of a certain material, but the cumulative ATP quantity is not displayed. However, the availability statement is based only on the cumulative ATP quantity. For example, the Stock: Single Material app does not show whether this stock has already been assigned to a certain requirements element. It should therefore not be used to determine availability of the material for a new requirements element.

Statements about the availability situation of a material can only be made based on the cumulative ATP quantity. The Availability Overview app can be used for this.

If sales order items are not available or are not available as requested, the delivery agreements defined in the order together with the availability situation determine the delivery dates. For example, if complete delivery is defined in the sales order and only one item cannot be confirmed as requested, delivery of the entire sales order waits until it can be delivered completely. If a partial delivery is allowed, the items that are available as requested can be delivered in advance and other items are subsequently delivered. Individual items can also be partially delivered.

You set the complete delivery indicator in the sales order header. It can be proposed from the business partner master record of the sold to party. You define the partial delivery agreement in the sales order item. It can be proposed from the business partner master of the sold to party or, with a higher priority, from the customer/material information record. You can change the default parameters manually when you enter a sales order.

If a material is planned using Material Requirements Planning, requirements control the procurement of the material.

In principle, a material can be planned in advance. Procurement is then always triggered by planned independent requirements. Stock is built up and sold by the warehouse. If the planning is correct, the material is then available as requested because the incoming sales orders were anticipated in the planned independent requirements.

However, customer requirements can also be relevant for MRP to compensate for planning errors. Whether a material is planned in advance, whether customer requirements are relevant for MRP, whether and how customer requirements consume planned independent requirements, is decided for each material and plant by specifying the planning strategy(s).

If customer requirements are relevant for MRP, the MRP run will recognize the shortage if there is a lack of availability and generate a procurement proposal. For externally procured materials, a purchase requisition is created and the purchasing department is asked to order. If the material is produced in-house, or if both procurement types are possible, the MRP run generates a planned order that is then converted into a production order or into a purchase requisition. These receipt elements become stock with the goods receipt posting. As a result, in a situation where a material is not initially available in an order due to the transfer of requirements and the receipt element generated by the periodically scheduled MRP run, these elements need to be taken into account in the calculation of the cumulative ATP quantity. Otherwise, the customer requirement could be confirmed at the latest after the goods receipt of these receipts into unrestricted-use stock. However, backorder processing is necessary for this, as requirements (for example, sales orders) do not repeat the availability check.