What Is Net Change MRP?
Also known as: net change planning, regenerative MRP, regenerative vs net change, incremental MRP
Definition
Net change MRP recalculates plans only for items affected by changes since the last run, such as new orders, receipts or BOM edits. Regenerative MRP discards and rebuilds the entire plan, which is slower but resets any accumulated drift.
Net Change MRP Explained
A regenerative run deletes unfirmed planned orders and recomputes every item from scratch. It guarantees consistency, but it takes time proportional to the whole database, so it is usually scheduled nightly or weekly. A net change run keeps a log of changed items and only replans those and the items that depend on them, which can complete in minutes and be run several times a day.
The advantage of net change is responsiveness. A large new sales order can be reflected in the plan within the hour, and planners see its effect on component supply without waiting for the night run. The risk is drift. If a change is not captured in the log, for example from a direct database update, an import or a skipped BOM recalculation, that item is never replanned and errors accumulate.
Most mature plants combine the two: a regenerative run at a quiet time, such as weekends, and net change runs during the working week. Systems expose this as an option on the planning run. Infor LN and SyteLine let administrators schedule planning runs with full or incremental scope, and SAP offers regenerative planning, net change planning and net change planning in the planning horizon.
Interactions with time fences and firm orders still apply. Both modes respect firmed orders and fences, but a net change run can produce a flurry of action messages if demand changes are frequent. Choosing frequency is a balance between currency and planner workload.
Why It Matters
- It determines how current the plan is when a large order lands mid-day.
- Run duration and database load drive when planning can be scheduled around other batch jobs.
- Drift in net change mode is a hidden cause of wrong requirements until a full run resets it.
- The right mix reduces nightly batch windows and can enable near real-time replanning.
In Practice
Example: a full regenerative run takes 6 hours and runs Saturday night. During the week, net change runs at noon and 6 pm take 15 minutes each and cover items touched by new orders and receipts. If a Monday report shows a part that never replans, planners check whether it bypassed the change log, then force a full run.
Frequently Asked Questions
Which is faster, net change or regenerative MRP?
Net change, because it processes only changed items and their dependents. A regenerative run processes every planned item and takes much longer.
Why run a regenerative MRP at all?
It clears accumulated drift and picks up changes that bypassed the change log. Many plants run one weekly alongside daily net change runs.
Does net change MRP replace firm planned orders?
No. Firm planned orders and time fences are respected in both modes. Only the scope of recalculated items changes.
Related Terms
MRP (Material Requirements Planning)
MRP (Material Requirements Planning) is the ERP calculation that explodes demand through bills of materials, nets it against on-hand and on-order inventory, and offsets by lead time to produce timed purchase and work order suggestions.
Planned Order
A planned order is a system-generated supply proposal that MRP creates to cover a net requirement. It has a quantity and dates but is not yet a committed job, production order or purchase order, and MRP can delete or reschedule it on every run.
MRP Action Messages
MRP action messages are exception prompts generated by the planning run, telling planners to release, reschedule in, reschedule out, change quantity or cancel existing orders so supply matches current demand.
Planning Time Fence
A planning time fence is a number of days from today inside which MRP will not automatically create or change planned supply. Changes in that window need planner approval, which keeps near-term production stable while the outer horizon remains flexible.
Go Deeper
SyteLine MRP Health Check
Diagnose why your SyteLine MRP output is noisy or ignored, scoring data accuracy, parameters, and planner behavior across ten dimensions.
Free ToolMRP Nervousness Assessment
A 10-question diagnostic that scores how badly your MRP plan churns between runs - and pinpoints which levers will stabilize it.
SyteLine MRP Parameters Tuning Guide
Optimize SyteLine MRP parameters including order policies, lot sizing, safety stock, and lead times for accurate material requirements planning results.
Infor LN MRP Planning Configuration Guide
Configure MRP planning in Infor LN with planning parameters, order policies, safety stock rules, and demand pegging for optimal material requirements.
SyteLine Multi-Plant MRP Planning Configuration
Configure multi-plant MRP planning in Infor SyteLine with cross-site demand netting, inter-plant supply relationships, and consolidated planning runs.
Working with Net Change MRP in a live environment? Our engineers do this every day - and our AI agents automate most of it.