SAP Materials Management (MM)

This skill enforces correct MM configuration, procurement discipline, and inventory accuracy. Every procurement transaction depends on complete master data — incomplete material masters, missing info records, or bypassed three-way match create downstream failures in FI, CO, and PP that are expensive to unwind.

Content Routing

Iron Laws

1. NEVER SKIP THREE-WAY MATCH VERIFICATION. Every vendor invoice (MIRO) must be matched against the purchase order (price, quantity, conditions) and the goods receipt (quantity, delivery date) before payment is approved. Bypassing three-way match — even for "trusted" vendors or urgent payments — removes the fundamental financial control against overpayment, duplicate payment, and fraud.
2. ALWAYS COMPLETE REQUIRED MATERIAL MASTER VIEWS BEFORE PROCUREMENT BEGINS. A material master missing the Purchasing view, MRP view, or Accounting view will block purchase order creation, MRP planning, or goods receipt valuation respectively. Incomplete material master data is the most common root cause of procurement failures in go-live.
3. NEVER CREATE A PURCHASE ORDER WITHOUT SOURCE DETERMINATION OR DOCUMENTED JUSTIFICATION. Purchase orders should reference a contract, scheduling agreement, source list, or quota arrangement. An undocumented PO without a source bypasses purchasing controls, makes price validation impossible, and creates audit findings.
4. ALWAYS RUN MRP WITH VERIFIED MASTER DATA. MRP (MD01/MD02) reads BOM, routing, purchasing info records, and planning parameters. Running MRP with incomplete or incorrect master data generates thousands of incorrect procurement proposals that take hours to correct manually. Verify master data completeness before any MRP run in production.
5. NEVER POST A GOODS RECEIPT WITHOUT REFERENCE TO A PURCHASE ORDER. Unplanned goods receipts (free GR without PO reference) bypass all purchasing controls including price, quantity, and vendor validation. Always post GR via MIGO with reference to the PO (movement type 101).

Rationalization Table

Red Flags

Watch for these in your own reasoning — each signals an Iron Law violation:

• "We can create the PO now and add the source list later..." → Source determination should precede PO creation in a controlled procurement environment. Retroactive source lists do not control already-created POs.
• "Let's post the GR without a PO reference and match it up later..." → Movement type 501 (GR without reference) bypasses all PO controls. Use 101 with PO reference unless a documented exception process exists.
• "MIRO is taking too long — let's just post an FI invoice..." → MIRO is not optional for PO-referenced invoices. FI-only posting leaves the PO and GR/IR account in an incorrect state.
• "The material master only needs Basic Data and Purchasing for now..." → MRP will fail to plan it; valuation will fail at GR; invoicing will fail at MIRO. Define all required views from the start.
• "MRP ran last week, let's reuse those results..." → MRP results must be regenerated after any master data change, BOM update, or demand change. Stale MRP results cause procurement of wrong quantities.
• "This vendor doesn't have an info record but we know the price..." → Without a purchasing info record, MIRO price tolerance checks have no reference price. Create the info record (ME11) before the PO.

<HARD-GATE> Before advising on MM configuration or procurement process design: confirm the system version (ECC or S/4HANA), whether Extended Warehouse Management (EWM) is deployed (replacing WM), and whether the Business Partner model is active (mandatory in S/4HANA — vendor master managed via BP transaction, not MK01). These flags change master data transactions, inventory management behavior, and integration architecture significantly. </HARD-GATE>

Key Concepts

• Procure-to-Pay (P2P): The end-to-end procurement process: Purchase Requisition → RFQ (optional) → Purchase Order → Goods Receipt → Invoice Verification → Payment.
• Material Master: Central master data object with views by organizational level. Key views: Basic Data 1/2, Purchasing, MRP 1–4, Accounting 1/2, Costing 1/2, Storage, Warehouse.
• Business Partner (BP): In S/4HANA, vendors are managed as Business Partners with role FLVN01 (vendor) via transaction BP. Classic vendor transactions (MK01, XK01) are deprecated.
• Purchasing Info Record (ME11): Defines vendor-material relationship: price, conditions, delivery time, tolerance. Required for automated price proposals in PO and three-way match in MIRO.
• Source List (ME01): Defines valid supply sources for a material in a plant. MRP uses source list for automatic source determination in planned order conversion.
• GR/IR Clearing Account: GL account that records the liability between goods receipt (debit stock, credit GR/IR) and invoice receipt (debit GR/IR, credit vendor). Must balance at period-end.
• Movement Types: Control how stock quantities and values are updated. Key types: 101 (GR vs. PO), 201 (GI to cost center), 261 (GI to production order), 301 (stock transfer), 501 (GR without reference — restricted use).
• MRP (Material Requirements Planning): Calculates net requirements from gross demand minus available stock and supply, and creates procurement proposals (planned orders, purchase requisitions).

Transaction Codes

Key Tables and CDS Views

Procure-to-Pay (P2P)

Standard P2P Flow

1. Purchase Requisition (ME51N): Internal demand signal — generated manually or by MRP
2. Source Determination: Assign vendor from source list, contract, or quota arrangement
3. RFQ / Quotation (ME41/ME47): Optional — competitive bidding for non-contracted items
4. Purchase Order (ME21N): Legal commitment to vendor; references PR and source
5. Goods Receipt (MIGO, MT 101): Physical receipt; debits stock, credits GR/IR account
6. Invoice Verification (MIRO): Three-way match; debits GR/IR, credits vendor payable
7. Payment (F110): AP payment run clears vendor open items

Three-Way Match Logic (MIRO)

• Price match: Invoice price vs. PO conditions — tolerance checked per tolerance key
• Quantity match: Invoice quantity vs. GR quantity — over/under delivery tolerance
• If within tolerance: Invoice posts automatically
• If outside tolerance: Invoice blocked for payment; requires approval workflow (MRBR release)

Material Master Data

Required Views by Business Process

Valuation Classes and Price Control

• Valuation class links material type to GL accounts (automatic account determination)
• Price control S (standard) — recommended for finished/semifinished goods with product costing
• Price control V (moving average) — recommended for raw materials and trading goods

MRP

MRP Run Types

MRP Parameters (MRP 1 View)

• MRP type: PD (MRP), VB (reorder point), ND (no MRP)
• Lot size: EX (exact), WB (weekly), MB (monthly), FX (fixed)
• Safety stock: Buffer against demand/supply uncertainty
• Reorder point: Triggers procurement when stock falls below threshold (VB type only)

MD04 — Stock/Requirements List

Real-time view of supply and demand situation for a material. Shows: opening stock, planned orders, purchase requisitions, purchase orders, sales orders, production orders, planned independent requirements.

Inventory Management

Physical Inventory

1. Create inventory document (MI01) — freezes book inventory
2. Count physical stock
3. Enter count results (MI04)
4. Post inventory differences (MI07) — adjusts book inventory to physical count

Key Movement Types Reference

Integration Points

Best Practices

1. Maintain purchasing info records proactively — they are the price reference for POs, MIRO tolerance checks, and vendor comparison reports.
2. Use outline agreements (contracts/scheduling agreements) for repeat procurement — reduces PO creation effort and enforces negotiated prices.
3. Configure tolerance keys (OMR6) aligned with business risk appetite — too tight creates excessive blocking; too loose loses the control value.
4. Implement evaluated receipt settlement (ERS) for high-volume, trusted vendors — system auto-creates MIRO from GR without paper invoice; eliminates invoice processing overhead.
5. Monitor GR/IR clearing account aging weekly — items older than 30 days indicate process failures (GR posted, invoice not received, or vice versa) that require resolution before period close.

Procurement Scenarios

Standard Procurement (PR → PO → GR → IR)

Complete P2P flow:

• PR creation (ME51N), account assignment (cost center/asset/order)
• RFQ optional (ME41) for new materials
• PO creation (ME21N), release strategy approval
• Goods receipt (MIGO, movement type 101) posts to stock + GR/IR clearing
• Invoice verification (MIRO), three-way match: PO qty = GR qty = IR qty
• Document types: NB (standard), FO (framework), UB (stock transfer)

Contract Release Order

Outline agreements with release orders:

• Value contract (ME31K) — e.g., "€500,000 for Q1 services"
• Quantity contract — e.g., "10,000 units of material X"
• Scheduling agreement (ME31L) with delivery schedule
• Release order references the contract, tracks consumption against target
• No re-approval per release once contract approved

Third-Party Order

Direct vendor-to-customer delivery (no inventory touch):

• Sales order with item category TAS
• Schedule line category CS triggers PR automatically
• PR converted to PO with shipping address = customer
• Vendor ships directly to customer, sends ASN
• IR creates vendor payable; customer invoice from SD billing
• No goods movement in MM

Consignment

Vendor-owned stock held at buyer's plant:

• Consignment info record (ME11) with consignment conditions
• Consignment PO (ME21N, item category K)
• Goods receipt (MIGO, MvT 101) — stock held as K (consignment)
• Consumption triggers KB movement (consignment to plant stock) + liability
• Monthly settlement (MRKO) generates vendor invoice

Subcontracting

Vendor processes buyer-provided components:

• BOM for subcontracted material (CS01)
• PO with item category L (subcontracting)
• Provide components: MB1B movement type 541 (transfer to vendor stock O)
• GR of finished material: MIGO 101 auto-consumes components (MvT 543)
• Three-way match on PO value (service fee, not material value)

Release Strategy Configuration

Release strategies control procurement approval workflow:

• Release group — document class (M3 for PR, M1 for PO)
• Release code — approver role (K1 = Dept Head, K2 = Plant Manager)
• Release indicator — effect of release (can change, locked, etc.)
• Release prerequisite — sequence of approvals

Typical PR release strategy by value:

Configuration: OMGS (characteristic values), OMGQ (classification). Assignments via PFCG role.

Material Master Views Detail

MRP Parameters Reference

Common MM Issues

• Material ledger activation is irreversible — Changes costing/valuation approach; evaluate carefully before turning on
• Batch management activation is one-way — Cannot be deactivated once active; impacts all processes
• Split valuation complications — Multiple valuation types per material multiplies config complexity
• Source list mandatory (OME5) — If mandatory, PO creation blocked without a valid source; check OME5 config
• Output determination failures — Check NAST table for output status, MN04 for condition records, MN21 for output type config

Verification

This skill is complete ONLY when ALL of the following are true:

• [ ] Material master views confirmed complete for all intended business processes before procurement begins
• [ ] Three-way match configuration reviewed — tolerance keys, blocking reasons, and release workflow confirmed
• [ ] Purchase orders reference source determination (contract, source list, or documented exception)
• [ ] MRP master data (BOM, routing, info record, planning parameters) verified complete before MRP run
• [ ] GR/IR clearing account monitoring process defined and assigned to an owner for period-end
• [ ] Business Partner model confirmed active in S/4HANA (BP transaction) vs. ECC (MK01/XK01)

Evidence required: Material master view list, MIRO tolerance key configuration, MD04 stock/requirements list showing correct MRP output — not generic MM descriptions.

Next Skill

After completing MM work, invoke:

• fi — For GR/IR clearing, invoice posting to FI, and period-end close
• co — For purchase price variances, material ledger, and cost object assignments
• verification-before-completion — Before closing any MM deliverable

Related Skills

• fi — Financial Accounting: GR/IR clearing, invoice verification postings, AP payment
• co — Controlling: purchase price variances, material ledger, production order costs
• sd — Sales and Distribution: intercompany procurement, goods issue for delivery
• ewm — Extended Warehouse Management: physical goods movements, put-away, picking
• analytics — MM reporting: purchase order analytics, inventory analysis CDS views
• abap-cloud — Custom MM enhancements: BAdIs for pricing, output, and GR processing