MRP Run (MD01N / MD04): Net Requirements, Planned Orders and Purchase Requisitions

Business scenario

Sales has 300 EA of FG-2000 on order for next month. The plant has 50 EA in stock and keeps 20 EA as safety stock. RM-1000 (one per assembly) is bought from Demo Supplier Ltd.; 100 EA are in stock.

All companies, numbers and documents are fictional demo data.

Step-by-step flow

1. 01

   Demand arrives open in twin

   Sales orders add up to 300 EA of FG-2000 for next month.

   MRP plans against requirements, not against what people expect to need. If demand is not in the system, MRP does not see it.

2. 02

   Net requirements calculation open in twin

   300 required − 50 in stock + 20 safety stock = 270 EA short.

   The result — the shortage — is what MRP needs to plan new supply for.

3. 03

   Run MRP Live (MD01N) open in twin

   MRP Live plans FG-2000 first (low-level code 0), then its components.

   Components' requirements only exist once the parent's supply has been planned and its BOM exploded.

4. 04

   Planned order for the finished good open in twin

   Procurement type E (in-house), lot-for-lot: planned order 45700 for 270 EA, backward-scheduled from the requirement date.

   Lot-for-lot (EX) plans exactly the shortage. Fixed or periodic lot sizes would produce different quantities — configuration dependent.

5. 05

   BOM explosion open in twin

   The planned order needs 270 EA of RM-1000. 100 are in stock, so 170 EA are short.

   This is how demand for the finished good becomes demand for everything it is made of.

6. 06

   Cover the raw-material shortage open in twin

   RM-1000 is bought from a supplier (procurement type F). What does MRP create for the 170 EA?

   In-house materials get planned orders; externally procured materials get purchase requisitions (or planned orders when the creation indicator says so).

7. 07

   MRP only proposes open in twin

   MRP creates proposals — planned orders, requisitions, schedule lines. Executable orders are always created by a person or a follow-on job.

   And a bought-in material is not produced at all — its shortage is covered by purchasing.

8. 08

   Purchase requisition for the raw material open in twin

   Requisition 10012345 for 170 EA of RM-1000, due 10 days before production starts. Purchasing takes it from here.

   This is the hand-off from PP to MM purchasing: the requisition becomes a purchase order (ME57 / ME21N).

9. 09

   Review MD04 and exceptions open in twin

   The planner checks MD04: shortages are covered, no exception messages. Next step: convert the planned order (CO41) and order the steel.

   Planners work by exception: MRP proposes, people check the messages and decide what to firm, convert or reschedule.

10. 10

    Planning complete open in twin

    Demand 300 → planned order 270 → dependent requirement 270 → requisition 170. No stock moved, nothing was posted.

    MRP is the planning step that sits before both — it decides what to make, what to buy, how much and when.

SAP documents

Stock impact

This part of the process does not change stock.

Accounting impact

Movement type

This flow spans several documents rather than a single movement type.

Ensures materials are available for production and sales on time by calculating net requirements and creating procurement proposals, while keeping stock as low as possible.

Transactions & Fiori apps

Configuration

• MRP type

  Configuration dependent

  PD (deterministic MRP), VB (reorder point) and others decide whether and how a material is planned.

• Lot-size procedure

  Configuration dependent

  EX lot-for-lot, fixed, periodic or optimising lot sizes change the proposal quantity.

• Creation indicator for requisitions

  Configuration dependent

  Whether MRP creates purchase requisitions directly or planned orders for external procurement.

• Storage locations excluded from MRP

  Configuration dependent

  Stock in excluded storage locations is not counted as available.

• Strategy group

  Configuration dependent

  Make-to-stock vs make-to-order planning strategies decide how sales orders and forecasts consume each other.

Prerequisites

• MRP type (e.g. PD) and lot-size procedure on the material master MRP views
• Procurement type (E in-house, F external) and planned delivery / in-house production times
• BOM and production version for in-house materials
• Requirements in the system: sales orders, planned independent requirements, dependent requirements

Master data

Material master MRP views

MRP type, lot size, procurement type, safety stock, planning times.

Bill of material

Explodes planned orders into dependent requirements.

Source list / purchasing info record

Lets MRP assign a supplier to the requisition.

Organizational structure

• Plant 1000 (MRP is planned per plant or MRP area)
• MRP controller 001 (demo)

Tables

Integration

• SDSales orders are requirements; availability checks read the planning situation.
• MMRequisitions feed purchasing; stock and open purchase orders are receipts for MRP.
• PPPlanned orders are converted into production or process orders.

Common errors

• “MRP does not create any proposal despite a shortage”

  Likely causes: Material has no MRP type or MRP type ND; Material not flagged for planning after the change; Stock counted from a storage location that should be excluded

  Where to look: Material master MRP 1 view · MRP run log · Storage location MRP indicator

• “Requisitions created without a supplier”

  Likely causes: No source list or info record; Source list not MRP-relevant

  Where to look: Source list (ME01) · Purchasing info record

• “Exception 'start date in the past'”

  Likely causes: Planned delivery or in-house production time longer than the time left before the requirement

  Where to look: MD04 exception messages · Material master planning times

Troubleshooting

Something went wrong? Work through these checks in order. They are diagnostic questions, not configuration instructions — confirm changes with your system owner.

1. CHECK 1

   No proposals

   • Does the material have an MRP type?
   • Is there a requirement in the planning horizon?
   • Is the stock really unavailable, or counted from an excluded storage location?

2. CHECK 2

   Wrong quantities

   • Which lot-size procedure applies?
   • Is safety stock set as expected?
   • Are rounding values maintained?

3. CHECK 3

   Wrong dates

   • Check planned delivery time, GR processing time and in-house production time
   • Check the factory calendar

Interview questions

• Walk me through how MRP calculates a net requirement.

  For each material and date, MRP takes the requirements (sales orders, planned independent requirements, dependent requirements), subtracts available stock and firm receipts, and adds back safety stock it must protect. A negative available quantity is a shortage; MRP covers it with a proposal sized by the lot-size procedure and scheduled using the planning times.

• What does MRP create for in-house and externally procured materials?

  Planned orders for in-house materials (procurement type E). For external materials (F) it creates purchase requisitions, or planned orders that are later converted, depending on the creation indicator — and schedule lines when a scheduling agreement is the source.

• What is a low-level code and why does it matter?

  The lowest BOM level at which a material appears across all BOMs. MRP plans in low-level-code order so that every parent is planned and exploded before its components, guaranteeing all dependent requirements exist when a component is planned.

• What is MRP Live in S/4HANA?

  MD01N, the HANA-optimised MRP run that reads and writes in bulk on the database. It replaces the classic MD01/MD02/MD03 runs as the recommended option; the planning logic (netting, lot sizing, scheduling) is the same.

Quiz

Related processes

• 101Procure-to-Pay
• 261 · 101Production Order

References

• SAP SE — SAP Help Portal: Material Requirements Planning (MRP) (source)
• SAP SE — SAP Help Portal: MRP Live (source)
• SAP SE — SAP Help Portal: Stock/Requirements List (source)

Explanations are original. They summarize standard behaviour; always validate against your system's release and configuration.

Version history