SAP MM / P2P Source Determination Interview Questions

Interviewers use source determination to test depth rather than coverage: the follow-up question is almost always "why does the system behave that way?", and that is where prepared answers usually run out.

Source Determination is the MM process by which the system identifies the most appropriate supplier or supply source (contract, scheduling agreement, info record, or quota-arranged vendor) for a material requirement raised via purchase requisition. This topic covers the business purpose, master data drivers (source list, outline agreements, info records, quota arrangements), the automated and manual determination logic, configuration settings that control it, integration with requisition and purchase order processing, common errors and troubleshooting, and differences across ECC and S/4HANA deployments including Fiori-based apps.

This page carries 23 reviewed SAP MM / P2P source determination interview questions, each with a complete written answer and no sign-in required. The set breaks down into 1 foundational, 7 mid-level and 15 advanced questions, so you can start at the top for a first interview or skip ahead to the scenario-based items for a senior round.

If you can handle every question here without hesitating, source determination is unlikely to be what costs you an SAP MM / P2P interview — and the same reasoning pattern transfers to the neighbouring topics linked at the bottom of this page.

23 Source Determination questions with answers

easySource Determination

1. What is Source Determination in the context of Service Procurement, and how does it differ when applied to material versus service line items in a purchase requisition?

Source determination identifies possible sources (contracts, info records, scheduling agreements) for a requisition item using ME57/ME51N assignment or automatic source determination. For services, source lists and info records are less commonly maintained since service specifications vary per requirement, so contracts (with conditions) and RFQs are the dominant sources; automatic source determination is often disabled for service lines due to variable service masters and pricing.

mediumSource Determination

2. A buyer notices that the price shown on the purchasing info record does not match the last PO price for a material-vendor combination. Walk through how you would investigate this discrepancy.

Check if the info record was updated automatically (info update indicator in PO) or manually maintained; review conditions in ME13 for validity periods, price scales, and plant/purchasing org specificity. Verify if the PO used a contract or scheduling agreement overriding info record pricing, check for time-dependent conditions expiring, and confirm whether the info record is plant-specific or general or overridden by outline agreement.

mediumSource Determination

3. A plant maintains a source list with three approved vendors for a material, but purchase requisitions keep converting to POs for only one vendor despite the source list allowing all three. What should you check?

First check whether the source list entries are flagged as 'fixed' (only one vendor can be fixed at a time and it wins automatically), then check quota arrangement if it exists, since quota can override apparent source list flexibility. Also verify source list relevance indicator in material master purchasing view and whether MRP-generated requisitions default to the fixed source. If no fixed source exists, buyers should be manually selecting; if source determination is automatic, the system picks the fixed or highest-quota vendor.

mediumSource Determination

4. A company wants to apply a quota arrangement to distribute procurement of a material across two vendors, but the material is currently set up with a non-stock, non-valuated material type. Can quota arrangement be used in this scenario, and what material master settings must be verified?

Quota arrangement is driven by MRP and requisition/PO source determination logic, which requires the material to be MRP-relevant with a valid MRP type and procurement type set to external procurement; it is not dependent on inventory valuation. So a non-valuated material type can still use quota arrangement as long as MRP views are maintained and the quota usage indicator is active, but since no stock value posts, verify that account assignment on resulting POs is correctly defaulted since goods receipt won't hit standard valuated stock accounts.

mediumSource Determination

5. When designing the migration architecture for source lists in a project integrating S/4HANA with decentralized EWM, what considerations determine whether source lists should be migrated per plant or centrally, and how does this interact with EWM's own sourcing logic?

Source lists are plant-specific and control which vendor/contract combinations are valid for procurement at that plant, so migration should follow the plant structure rather than a single central load unless plants share identical sourcing. In decentralized EWM scenarios, EWM doesn't own source list logic itself—procurement sourcing remains in S/4HANA—but EWM-triggered replenishment or stock transfer orders still rely on the source list being correctly maintained per plant to avoid procurement determination errors during goods movement triggers.

mediumSource Determination

6. After migrating source lists to S/4HANA as part of a procurement transformation, buyers report that certain materials configured for automatic source determination are failing to find a valid source during requisition conversion, even though the source list appears populated correctly. What would you check?

I would check whether the source list entries have valid-from/valid-to date ranges covering the current date, since expired or future-dated entries won't be considered. I would also verify the 'fixed source' and MRP relevance indicators, and confirm the corresponding purchasing info record or contract referenced by the source list entry actually exists and is not expired, since a source list pointing to a missing or expired info record will fail source determination even though the source list itself looks correctly migrated.

mediumSource Determination

7. During cutover for a phased S/4HANA migration, purchasing info records and source lists must be loaded via migration objects while live PO approvals continue through an SAP BTP Integration Suite-managed Ariba interface. What sequencing and validation steps minimize hypercare disruption?

Sequence migration so master data objects (info records, source lists, contracts) load and are validated before opening the Ariba integration flows in BTP Integration Suite for that scope, preventing PO creation against incomplete pricing/source data. Freeze non-critical changes during cutover window, run migration object validation reports, and test a subset of end-to-end PO flows through Integration Suite before go-live. Establish a hypercare monitoring plan combining migration cockpit logs and Integration Suite message monitoring.

mediumSource Determination

8. Explain how quota arrangement integrates with MRP-driven procurement and how it interacts with purchasing master data to distribute demand across multiple vendors.

Quota arrangement splits requirement quantities among sources (vendors or plants) based on assigned quota percentages and quota base quantity; when MRP creates purchase requisitions, the system checks the quota arrangement (if source list requirement and quota usage are active) and proposes the vendor with the lowest quota rating (allocated quantity vs quota). It integrates with info records for pricing once the vendor is determined and can coexist with source list fixed entries if properly configured.

hardSource Determination

9. A purchase order for a critical material has multiple schedule lines sourced from two vendors via source determination (source list with quotas), and GR-based invoice verification is active. Partial goods receipts arrive from both vendors against overlapping schedule lines, and FI-AP now shows invoices blocked with quantity variances that don't match either vendor's actual delivery. As the architect, how would you diagnose and resolve this?

I would first check whether the PO was split into separate items per vendor (as source determination normally requires) rather than sharing schedule lines across vendors on one item, since GR-based IV matches invoices to GR quantities at item level, not vendor level. I'd review MIGO/MSEG postings per item to confirm which GR belongs to which vendor's delivery, then check invoice line references in MIRO to ensure invoices reference the correct PO item and GR document rather than an aggregated one. Root cause is typically a single-item PO incorrectly used for multi-vendor sourcing.

hardSource Determination

10. Design a source determination strategy for a global organization with multiple plants sourcing the same service category from regional preferred vendors, while allowing central contract compliance monitoring.

Establish central contracts (outline agreements) at the corporate purchasing organization level with plant-specific info records and source lists pointing to regional vendors, using scales or plant conditions where pricing differs regionally. Configure source list entries as relevant for MRP-driven or manual sourcing, and use quota arrangements if volume must be split across vendors. Enforce contract release via ME21N automatic sourcing based on source list/quota, while central procurement monitors compliance through reporting on contract release orders versus off-contract spend.

hardSource Determination

11. A plant using inbound delivery processing for scheduling agreements finds that source determination in the requisition-to-PO conversion keeps ignoring the source list entry marked as fixed, routing instead to a different vendor. How would you investigate this as an architect?

I'd verify the source list entry's validity period and the fixed indicator, then check whether a quota arrangement or outline agreement with a higher priority is overriding it, since quota arrangements can supersede a fixed source list entry depending on configuration. Next, I'd confirm the material's source determination indicator is active at plant level and that MRP-generated requisitions actually invoke source determination (not manually created reqs bypassing it). I'd also check for contract release order creation logic that may redirect sourcing independent of the source list, and review any custom BAdI/user-exit affecting source determination.

hardSource Determination

12. In a global source-to-contract process, how does contract hierarchy (centrally negotiated global contracts vs. local distribution contracts) impact source determination logic when a purchase requisition is created at a plant level?

A global contract negotiated centrally establishes pricing and terms at a header level, while distribution contracts release value/quantity to specific plants or purchasing organizations. Source determination at plant level checks the local distribution contract first (if maintained via ME33K's distribution function), falling back to source list entries or info records if no local contract exists. Architects must ensure central contract maintenance replicates correctly to distributed contracts to avoid conflicting pricing or duplicate sourcing paths across purchasing organizations.

hardSource Determination

13. Buyers report that certain purchase requisitions for services are not automatically picking up the negotiated contract as source of supply during source determination, forcing manual vendor selection each time. What are the likely root causes and how would you diagnose this?

Likely causes include the contract not being flagged relevant for source list/quota arrangement, missing or expired validity dates, plant or purchasing organization mismatch between the requisition and contract release scope, source list entries missing or marked as 'source list' without 'MRP relevant' flag, or the contract's material/service category not matching the requisition item precisely. Diagnosis involves checking the contract (ME33K) release documentation, source list (ME01/ME03), quota arrangement, and requisition account assignment/plant fields against contract scope.

hardSource Determination

14. In a global template rollout, how should field selection for purchasing info records be governed to balance mandatory pricing controls against country-specific tax and condition requirements?

Field selection for info records is controlled via field selection groups tied to the info record category and screen layout in config (OMEC/similar), combined with condition technique defaults for pricing fields. A governance approach defines a global template with mandatory core fields (net price, price unit, purchasing org) locked centrally, while country-specific fields like tax classification or delivery costs are made conditionally required through validation or workflow rather than hardcoded field status, preserving template stability while allowing localization.

hardSource Determination

15. A global organization needs an architecture for vendor returns where, once a quality-related return is initiated against a centrally negotiated contract, source determination must temporarily prevent that vendor's contract from being auto-sourced for replenishment purchase requisitions until the quality issue is resolved and closed in FI-AP via credit memo. How would you design this?

Since source determination (source list, quota arrangement, contract-based sourcing) has no native quality-hold linkage, design a governance layer using a blocked source list entry or contract blocking indicator triggered by a quality notification workflow, combined with a purchasing block on the vendor or outline agreement item. Integrate with QM notification status changes to automatically flag the source list entry as blocked, forcing manual sourcing review, and reconcile FI-AP credit memo posting to the original return PO before releasing the block programmatically or via a governance approval step.

hardSource Determination

16. In a global governance model, how should field selection for source list maintenance be controlled to prevent unauthorized changes to fixed source or MRP-relevance flags across regions, while still allowing local buyers operational flexibility?

Field selection for source list records is governed largely through authorization objects and process controls rather than the same field-status-group mechanism as material master, since source list screens have limited configurable field control. Governance should combine authorization restrictions on maintaining the fixed vendor indicator, change documentation/audit trail review, and a global template defining which fields (fixed source, validity period, MRP relevant) are centrally owned versus locally editable, with periodic reconciliation reports flagging deviations.

hardSource Determination

17. A purchase requisition configured for automatic source determination is proposing an unexpected vendor, or in some cases no source at all, when converting to a purchase order. Walk through your diagnostic approach across master data and configuration to isolate the root cause.

Start by checking whether the 'source determination' indicator is set at PR item level, then verify the source list (ME01) for validity dates, plant scope, and fixed/blocked indicators for the material-vendor combination. Check quota arrangements (MEQ1) if multiple sources qualify, since quota rating can override expected source list entries. Validate outline agreement or info record validity periods, purchasing organization/plant assignment, and whether multiple unblocked entries create ambiguity requiring manual selection instead of automatic assignment.

hardSource Determination

18. After go-live, business reports that a critical material is being sourced entirely from a single vendor even though quota arrangement was configured to split 60/40 across two vendors. Purchase order history confirms 100% volume to one vendor over three months. How would you diagnose this?

Check the quota rating formula and current cumulative quota base quantity (quota base quantity, allocated quantity) in the quota arrangement item, since ratings recalculate only as PRs/POs are created and one vendor may have started with a large negative allocation advantage. Also verify quota validity dates haven't expired, that quota arrangement usage indicator is active in the material master, and that no fixed source list entry or existing open contract is overriding quota-based source determination for that material/plant combination.

hardSource Determination

19. A client integrating Ariba with S/4HANA is using a make-to-order production scenario where Ariba-sourced components trigger PP requisitions. During go-live, purchase requisitions generated by MRP for these PP-driven components are not flowing correctly to Ariba for sourcing. What integration points would you investigate?

Check the purchasing category/document type mapping in the Ariba integration configuration—only requisitions flagged for external sourcing (via source of supply category or Ariba-relevant document type) are routed through CIG to Ariba. Verify that PP-generated requisitions inherit the correct account assignment and item category expected by the Ariba interface, and confirm the CIG middleware mapping includes MRP-sourced requisition types, since Ariba integration is often configured only for manually created requisitions initially.

hardSource Determination

20. During quotation comparison, procurement leadership notices that source determination is automatically defaulting to a higher-priced vendor despite better quotes from alternate vendors on the same RFQ. What configuration and master data areas should be investigated to diagnose this?

Investigate the source list and quota arrangement settings, as a fixed or blocked source list entry can override price-based selection regardless of quotation comparison results. Also check info records for automatic source determination flags and any purchasing organization-level source determination indicator on the material master. Review whether quotation comparison prices were properly transferred to the info record after RFQ rejection/acceptance, since source determination for follow-on POs relies on info record and source list data, not directly on RFQ price comparison.

hardSource Determination

21. A client uses source lists heavily tied to PP-driven MRP scheduling agreements across plants. During S/4HANA migration, what considerations are critical for migrating source list data without disrupting production planning?

Source lists must be migrated with correct validity periods and fixed-source indicators consistent with the linked scheduling agreements, since MRP run relies on the source list to determine the valid supplier for planned orders. Ensure the migration sequence loads vendor BP records and scheduling agreements before source lists, and validate that MRP-relevant flags (fixed source, blocked) match legacy behavior to avoid MRP generating incorrect or unassigned purchase requisitions post-cutover.

hardSource Determination

22. A centrally negotiated service contract expires mid-quarter and source determination automatically re-routes new release orders to a backup vendor per the source list, but the PO output (message type NEU) is not transmitting to the new vendor, and FI-AP is now seeing GR/IR mismatches on invoices referencing the old vendor's PO numbers. As the architect, how would you diagnose and fix this?

Check whether the new vendor has valid output condition records (partner function VN, purchasing organization, document type) in NACE/CO03-style condition maintenance; source list switch does not automatically create output records for a new partner. Verify the source list validity dates and info record link driving the switch, confirm the release order actually references the new vendor's PO number, and check GR/IR account assignment consistency between old and new vendor POs before resolving FI-AP mismatches via manual invoice correction or MR11 cleanup.

hardSource Determination

23. During go-live, purchasers report that certain materials are not defaulting the preferred vendor even though a source list entry exists. Diagnose the likely root causes.

Check whether the source list entry has the fixed/preferred indicator set and is within validity dates; verify source list requirement indicator is active at plant level (OMB5 or material master purchasing view) forcing source determination checks; confirm no blocking entry (X) exists preventing that vendor, and check if MRP-generated requisitions bypass source list due to missing plant-level activation or quota arrangement interference overriding the fixed source.

Next practice step

Practice with Interview AI Take a mock test

SAP MM / P2P Source Determination Interview Questions

23 Source Determination questions with answers

1. What is Source Determination in the context of Service Procurement, and how does it differ when applied to material versus service line items in a purchase requisition?

2. A buyer notices that the price shown on the purchasing info record does not match the last PO price for a material-vendor combination. Walk through how you would investigate this discrepancy.

3. A plant maintains a source list with three approved vendors for a material, but purchase requisitions keep converting to POs for only one vendor despite the source list allowing all three. What should you check?

4. A company wants to apply a quota arrangement to distribute procurement of a material across two vendors, but the material is currently set up with a non-stock, non-valuated material type. Can quota arrangement be used in this scenario, and what material master settings must be verified?

5. When designing the migration architecture for source lists in a project integrating S/4HANA with decentralized EWM, what considerations determine whether source lists should be migrated per plant or centrally, and how does this interact with EWM's own sourcing logic?

7. During cutover for a phased S/4HANA migration, purchasing info records and source lists must be loaded via migration objects while live PO approvals continue through an SAP BTP Integration Suite-managed Ariba interface. What sequencing and validation steps minimize hypercare disruption?

8. Explain how quota arrangement integrates with MRP-driven procurement and how it interacts with purchasing master data to distribute demand across multiple vendors.

10. Design a source determination strategy for a global organization with multiple plants sourcing the same service category from regional preferred vendors, while allowing central contract compliance monitoring.

11. A plant using inbound delivery processing for scheduling agreements finds that source determination in the requisition-to-PO conversion keeps ignoring the source list entry marked as fixed, routing instead to a different vendor. How would you investigate this as an architect?

12. In a global source-to-contract process, how does contract hierarchy (centrally negotiated global contracts vs. local distribution contracts) impact source determination logic when a purchase requisition is created at a plant level?

13. Buyers report that certain purchase requisitions for services are not automatically picking up the negotiated contract as source of supply during source determination, forcing manual vendor selection each time. What are the likely root causes and how would you diagnose this?

14. In a global template rollout, how should field selection for purchasing info records be governed to balance mandatory pricing controls against country-specific tax and condition requirements?

16. In a global governance model, how should field selection for source list maintenance be controlled to prevent unauthorized changes to fixed source or MRP-relevance flags across regions, while still allowing local buyers operational flexibility?

17. A purchase requisition configured for automatic source determination is proposing an unexpected vendor, or in some cases no source at all, when converting to a purchase order. Walk through your diagnostic approach across master data and configuration to isolate the root cause.

18. After go-live, business reports that a critical material is being sourced entirely from a single vendor even though quota arrangement was configured to split 60/40 across two vendors. Purchase order history confirms 100% volume to one vendor over three months. How would you diagnose this?

20. During quotation comparison, procurement leadership notices that source determination is automatically defaulting to a higher-priced vendor despite better quotes from alternate vendors on the same RFQ. What configuration and master data areas should be investigated to diagnose this?

21. A client uses source lists heavily tied to PP-driven MRP scheduling agreements across plants. During S/4HANA migration, what considerations are critical for migrating source list data without disrupting production planning?

23. During go-live, purchasers report that certain materials are not defaulting the preferred vendor even though a source list entry exists. Diagnose the likely root causes.

Related lesson

Related topics

Next practice step