Zero-Click Answer
Standard costs should be rebuilt during an ERP implementation when the existing standards no longer reasonably represent how products are manufactured or when management cannot demonstrate that the assumptions behind them remain valid. An ERP conversion does not automatically require new standards; well-maintained standards can often be validated and migrated. But when bills of material, routings, labor rates, overhead rates, yields, scrap assumptions, or production volumes have materially changed, simply transferring the existing standards can carry known or hidden costing problems into the new system. For ERP implementers, the decision should not be “old standards or new standards?” It should be “which standards can be validated and migrated, which need updating, and which require a structural rebuild before they become new-system configuration?”
What the ERP Is Being Asked to Do
A manufacturing ERP may use standard costs for several purposes.
Depending on the manufacturer’s costing methodology and system configuration, standards may influence:
- Raw-material costs
- Labor costs
- Machine costs
- Manufacturing overhead
- Work-in-process
- Finished goods inventory
- Cost of goods sold
- Manufacturing variances
- Product-margin reporting
A standard product cost can incorporate several assumptions:
Material + Labor + Machine + Overhead + Other Manufacturing Cost = Standard Product Cost
Each component may depend on additional master data.
Material cost can depend on the BOM, quantities, units of measure, purchase-cost assumptions, scrap, and yield.
Labor and machine cost can depend on routings, work centers, setup times, run times, and rates.
Overhead can depend on cost pools, allocation drivers, and capacity or production-volume assumptions.
This creates an important implementation issue.
The existing standard cost is not simply a number to migrate.
It is the financial result of a collection of underlying manufacturing assumptions.
Before that number becomes part of the new ERP, management should understand whether those assumptions still represent the operation.
What May Be Happening Operationally
Standard costs often age gradually.
There may never be a single event when management concludes:
“Our standards are now wrong.”
Instead, manufacturing changes incrementally.
A new machine is installed.
A production line becomes faster.
Labor requirements decline.
A material supplier changes.
Scrap improves.
Packaging changes.
Production moves between work centers.
A product is redesigned.
Overhead increases.
Production volume changes.
Each individual change may appear manageable.
Over time, however, the cumulative effect can create a meaningful gap between the standard cost and manufacturing reality.
For example, a product may have been established when production required:
- 12 pounds of material
- 45 minutes of labor
- 30 minutes of machine time
Several years later, the actual process may require:
- 11 pounds of material
- 25 minutes of labor
- 50 minutes of machine time
The total standard cost might still appear reasonably close to actual cost because some errors offset others.
That does not mean the standard is reliable.
Material may be overstated while machine cost is understated.
Management could therefore receive misleading variance information even if the total product cost appears reasonable.
An ERP implementation can expose these inconsistencies because the new system requires the manufacturer to explicitly define the components behind the standard.
Where the Implementation Risk Appears
The decision to migrate or rebuild standards can create several implementation risks.
Existing Standards Are Assumed to Be Valid
The legacy ERP contains a standard cost.
That cost has been used for inventory and financial reporting.
Therefore, it is treated as an approved business requirement.
But historical use is not the same as current validation.
The implementation can unintentionally convert:
Existing Standard → Migrated Standard → New ERP Standard
without evaluating the manufacturing assumptions in between.
Rebuilding Everything Can Create Unnecessary Risk
The opposite approach can also be problematic.
Rebuilding every standard during an ERP implementation can substantially expand scope.
It may require:
- BOM validation
- Routing studies
- Labor-rate development
- Machine-rate analysis
- Overhead redesign
- Scrap and yield review
- Capacity analysis
- Financial validation
If the existing standards are well maintained, a complete rebuild may add cost, complexity, and schedule risk without providing equivalent value.
The correct answer is therefore not automatically to rebuild everything.
Costing Changes Become Difficult to Separate From ERP Changes
If the company changes ERP systems and completely changes its standard costs at the same time, post-go-live differences can become difficult to explain.
Management may see a product margin change and ask:
“Is this because of the new ERP or because we changed the standard?”
That does not mean standards should never be rebuilt during implementation.
It means changes should be documented and tested so management can distinguish:
System Change from Economic Assumption Change.
Inventory Can Be Affected
Changing standard costs can affect the valuation of existing inventory.
Depending on the costing methodology and accounting treatment, changes may influence:
- Raw materials
- WIP
- Finished goods
- Cost of goods sold
- Revaluation accounts
- Manufacturing variances
Finance should understand these implications before the revised standards are activated.
Go-Live Can Begin With Unstable Economics
If standards are still being debated immediately before go-live, testing may be occurring against moving targets.
Configuration may be correct one week and require retesting the next because the costing assumptions changed.
Cost-design decisions should therefore be resolved early enough to support meaningful financial testing.
What Implementers Should Look For
Several conditions can help determine whether standards should be migrated, updated, or rebuilt.
1. Existing standards are routinely maintained and reconciled to operations.
This generally supports validation and migration rather than automatic rebuilding.
2. BOMs and routings are materially outdated.
If the underlying manufacturing master data is unreliable, the standards derived from it deserve additional scrutiny.
3. Manufacturing has changed significantly since the standards were established.
Automation, equipment, labor, facilities, product mix, sourcing, or production-method changes can justify rebuilding affected standards.
4. Large recurring variances are accepted as normal.
Persistent material, labor, overhead, or absorption variances may indicate that standards no longer provide a useful operating benchmark.
5. Management does not trust product margins.
If product profitability is already questioned, migrating the same standards may reproduce the same problem in the new ERP.
Questions to Ask the Manufacturer
The implementer can help management determine the appropriate path by separating the decision into several areas.
Standard-Cost Governance
- When were standard costs last comprehensively reviewed?
- How frequently are standards updated?
- Who owns standard-cost maintenance?
- What approvals are required before standards change?
- Are changes documented?
Material Standards
- Are BOM quantities current?
- Are purchase-cost assumptions current?
- Are units of measure correct?
- Are scrap and yield assumptions realistic?
- Have major sourcing changes occurred?
Labor and Machine Standards
- Are routing times current?
- Have production methods changed?
- Has automation changed labor requirements?
- Are labor rates current?
- Are machine rates based on current operating economics?
Overhead
- When were overhead rates last recalculated?
- Are cost pools still appropriate?
- Are allocation drivers still relevant?
- What production or capacity assumptions support the rates?
- Are recurring absorption variances occurring?
Variances
- What are the largest recurring manufacturing variances?
- Are they caused by operating performance or outdated standards?
- Do variances consistently move in one direction?
- Does management use the variance information to make decisions?
Product Margins
- Does management trust current product-margin reporting?
- Which products or product families create the greatest concern?
- Are reported margins consistent with management’s operational experience?
- Are pricing decisions being made using the existing standards?
ERP Conversion
- Which standards can be migrated without modification?
- Which require targeted updates?
- Which product families require a complete rebuild?
- How will changes be documented?
- How will old and new costs be compared before go-live?
A particularly useful question is:
“If we migrate the existing standard costs unchanged, which known costing problems will also move into the new ERP?”
The answer helps determine whether migration is preserving a reliable structure or preserving a problem.
Cost Integrity™ Perspective
Cost Integrity™ suggests three possible paths for standard costs during an ERP implementation:
1. Validate and Migrate
Use this approach when:
- Master data is current
- Standards are regularly maintained
- Variances are understood
- Costing methodology remains appropriate
- Management trusts the resulting product economics
The objective is to prove that the existing architecture is sufficiently reliable before transferring it.
2. Update and Migrate
Use this approach when the architecture remains appropriate but specific assumptions require correction.
Examples may include:
- Updated material prices
- Revised labor rates
- Changed routing times
- New scrap assumptions
- Revised overhead rates
The structure remains.
The inputs change.
3. Rebuild
A structural rebuild becomes more appropriate when:
- BOMs or routings are unreliable
- Cost pools no longer represent the operation
- Allocation drivers are inappropriate
- Capacity assumptions are unrealistic
- Standards have not been maintained
- Recurring variances have become normal
- Management does not trust product margins
In that situation, simply updating a few rates may not solve the underlying problem.
The cost architecture itself requires attention.
The Cost Integrity™ sequence becomes:
Assess Existing Standards → Validate Underlying Assumptions → Classify → Migrate / Update / Rebuild → Configure → Test → Govern
This approach avoids both extremes.
It does not assume that old standards are correct simply because they exist.
It also does not assume that every ERP implementation requires a complete cost-system redesign.
Bottom Line
ERP implementation creates a natural decision point for standard costing.
The manufacturer has three choices:
Validate & Migrate
Update & Migrate
Rebuild
The correct choice depends on the reliability of the existing cost architecture.
If standards are current, supported by accurate BOMs and routings, governed consistently, and producing meaningful variance and margin information, migration may be appropriate.
If individual assumptions have changed, targeted updates may be sufficient.
If the underlying cost architecture no longer represents manufacturing reality, a rebuild may be necessary before the new ERP institutionalizes the problem.
For ERP implementers, the key question is therefore not:
“Should we migrate the existing standard costs?”
It is:
“What evidence do we have that these are the standards management wants the new ERP to rely upon?”
That question separates data migration from economic validation—and helps prevent the new ERP from beginning its life with an old costing problem.
FAQ
Does every ERP implementation require a standard-cost rebuild?
No. Well-maintained standards supported by reliable master data and appropriate costing methodology may be validated and migrated. A rebuild should be driven by the condition of the existing cost system, not simply by the ERP conversion.
What is the difference between updating and rebuilding standard costs?
An update changes individual assumptions—such as material prices, labor rates, routing times, or overhead rates—while preserving the basic cost architecture. A rebuild reevaluates the underlying structure, including cost pools, drivers, standards, capacity assumptions, and potentially the costing methodology itself.
Should standard costs be rebuilt before or after ERP go-live?
When a structural rebuild is necessary, the costing design should generally be resolved early enough to support configuration and meaningful pre-go-live testing. Leaving fundamental cost-design decisions until after go-live can create rework and make financial results harder to interpret.
How should ERP implementers handle standard-cost decisions?
The implementer should help identify where costing requirements are incomplete or inconsistent, but management should own the economic and accounting decisions. Once the requirements are defined and approved, the ERP team can configure and test the system against those requirements.