After updating our supply planning parameters last week, the MRP run is no longer considering safety stock levels when generating planned orders. We’re seeing inventory levels drop below safety stock thresholds without any replenishment orders being created.
Our coverage groups are configured with minimum inventory settings, and the safety stock journal entries are active and approved. The MRP run completes without errors, but the planned orders only cover demand requirements without accounting for the safety stock buffer. This is causing potential inventory shortages for critical components.
The issue started after we modified the coverage group settings to optimize lead times. I’m concerned we inadvertently disabled something in the MRP configuration that controls how safety stock is factored into planning calculations. Has anyone experienced MRP ignoring safety stock after making coverage group changes?
Check your coverage group minimum settings. In Master planning > Setup > Coverage > Coverage groups, verify that the “Minimum” field is set correctly and the “Minimum key” is properly defined. If you changed the coverage code from “Min/Max” to “Requirement” or “Period”, that would explain why safety stock is being ignored. The coverage code determines whether MRP considers safety stock levels during planning runs.
I had a similar problem and it turned out to be the MRP plan configuration itself. Go to Master planning > Setup > Plans > Master plans and check the “Coverage time fence” settings. If the coverage time fence is shorter than your lead times, MRP won’t generate orders far enough in advance to maintain safety stock. Also look at the “Positive days” and “Negative days” settings - these affect how MRP consolidates requirements and can impact safety stock calculations.
Another thing to check is whether your items have the coverage group properly assigned at the item coverage level. Sometimes global coverage group changes don’t cascade down to existing item coverage records. Go to Master planning > Setup > Coverage > Item coverage and verify that your critical items are actually using the updated coverage group, not an override setting that’s still pointing to old configuration.
I reviewed the coverage groups and they’re still set to “Min/Max” coverage code. The minimum field shows the correct values. However, I noticed the “Fulfill minimum” option - could this be the issue? It’s currently set to “Today’s date” but I’m not sure if that’s correct for our planning horizon.
Based on your description, the issue is likely a combination of coverage group settings and safety stock journal configuration that got misaligned during your parameter update. Let me walk through the complete solution addressing all three focus areas.
First, verify your coverage group settings are correctly configured for safety stock planning. In Master planning > Setup > Coverage > Coverage groups, ensure these specific settings:
- Coverage code must be “Min/Max” (not “Requirement” or “Period”)
- Minimum field should reference your safety stock calculation method
- “Fulfill minimum” should be set to “Today’s date + coverage time fence” - this is crucial because it tells MRP to maintain safety stock throughout your planning horizon, not just for today
- Positive days should be set to at least your average lead time to allow proper order consolidation
- The “Override minimum” checkbox should be UNCHECKED unless you have specific items that need different treatment
Second, review your safety stock journal entries to ensure they’re active and properly configured. Go to Master planning > Master planning > Safety stock journal and verify:
- All journal lines are posted and approved (status should be “Approved”, not “Created” or “Calculated”)
- The “From date” on journal entries is not in the future - MRP ignores future-dated safety stock
- Minimum quantity values are positive and realistic for your demand patterns
- There are no overlapping journal entries with conflicting minimum values for the same items
- The “To date” field is either blank or far enough in the future to cover your planning period
Third, check the MRP configuration parameters that control how safety stock is calculated during planning runs. In Master planning > Setup > Plans > Master plans:
- Coverage time fence should be at least equal to your longest lead time plus safety stock replenishment time
- Explosion time fence must be longer than coverage time fence
- “Use reduction keys” should be disabled if your safety stock is constant, or properly configured if it varies by season
- Under the “General” tab, verify “Include safety stock” is checked - this is a master switch that can disable safety stock planning entirely
The most common cause when safety stock suddenly stops being considered is the “Fulfill minimum” setting getting changed to “Today’s date” during coverage group updates. This causes MRP to only consider safety stock for immediate requirements, not future planning periods. Changing it to “Today’s date + coverage time fence” ensures safety stock is maintained throughout your planning horizon.
After making these corrections, run a full MRP regeneration (not just a net change) to ensure all planned orders are recalculated with the corrected settings. The regeneration will clear any cached planning data that might still be using the old configuration. You should then see planned orders that maintain inventory above your safety stock minimums throughout the planning period.
The “Fulfill minimum” setting is critical here. If it’s set to “Today’s date” and your safety stock journal entries have future effective dates, MRP won’t consider them. Change it to “Today’s date + coverage time fence” or “First issue” depending on your planning strategy. Also verify that your safety stock journal lines don’t have any negative adjustments that might be offsetting the safety stock requirements. Check Master planning > Master planning > Safety stock journal to review all active entries.