A manufacturing internal audit follows the flow from buying raw material to shipping the finished product. The biggest risk areas are procurement, inventory, production and costing, fixed assets and plant-level controls. Tests should mix document checks with physical verification at the plant.
Last reviewed: 17 October 2026. Facts checked. We searched for common manufacturing audit focus areas (procurement, inventory and cost of goods sold, production costing, fixed assets, multi-site and ERP risks) and for cost audit applicability under Section 148 of the Companies Act, 2013. The sources were practitioner articles and job postings, which we treat as indicative. We did not open the Cost Records and Audit Rules and cite no turnover thresholds. We also did not verify CARO 2020 or Section 138 details here.
What makes manufacturing different
A trading business buys and sells. A manufacturer also converts material into goods. That adds extra steps where value can be lost: wastage, rework, idle time, and wrong costing. It also means more physical assets, more locations and more reliance on the ERP.
Map the process first
Draw the main chain and pick control points.
| Stage | Key control question |
|---|---|
| Planning | Is production planned from demand and stock? |
| Procurement | Are vendors approved and prices competitive? |
| Receiving | Is what arrives checked against the order? |
| Storage | Is stock safe, counted and recorded? |
| Production | Are material use and yield tracked against standards? |
| Quality | Are defects caught and recorded? |
| Dispatch and billing | Is every shipment invoiced? |
| Finance | Is cost allocated correctly? |
Procurement tests
- Are vendors approved, and is the approval documented?
- Are purchase orders raised before goods are received?
- Do orders, receipts and invoices match (three-way match)?
- Review splitting of orders to avoid approval limits.
- Check rate changes against contracts.
- Look at vendor concentration and related-party vendors.
- Review advances paid to suppliers and their ageing.
Inventory tests
Inventory is often a large part of the balance sheet, so small errors matter.
- Attend physical counts and test count sheets against the system.
- Test cut-off between receipts, issues and dispatches.
- Review slow-moving, obsolete and damaged stock, and the policy for provision.
- Check that scrap and by-products are recorded and sold with approval.
- Test inter-plant and third-party stock held outside the factory.
- Review stock adjustments and who approved them.
Production and costing tests
- Compare actual material use with the bill of materials (BOM). Investigate gaps.
- Review yield and wastage against standards.
- Test how labour and overheads are allocated to products.
- Check that standard costs are updated with approval.
- Review work-in-progress valuation.
- Look at manual journals that change inventory or cost of goods sold. These are higher risk.
Where cost audit applies to your company under the Companies Act, coordinate with the cost auditor to avoid duplicate work. Check the current rules to see whether it applies.
Fixed asset tests
- Are additions backed by invoices and approvals?
- Are capital items separated from repairs?
- How old is capital work in progress, and why has it not been capitalised?
- Is physical verification done, and are differences resolved?
- Is depreciation computed correctly?
- Are idle or scrapped assets reported and disposed of properly?
Quality, safety and compliance
- Review customer complaints and returns, and the trend over time.
- Check that safety, pollution and factory licences are valid.
- Test that statutory payments for labour and contract workers are made.
- Review environmental and waste records.
For regulated quality systems, see our ISO internal audit step-by-step guide.
Multi-site and IT risks
- Do plants follow the same policies, or has each built its own way of working?
- Who can change master data in the ERP, such as BOMs, rates and stock codes?
- Are there interfaces between plant systems and the ERP that fail silently?
- Are access rights reviewed when people change roles?
Analytics that help
- Duplicate invoices and duplicate vendors.
- Purchase prices that jump between orders.
- Stock movements posted outside working hours.
- Negative stock balances.
- Production scrap rates by shift or machine.
Our manufacturing audit workbook and automation guide for manufacturers go deeper.
Planning tips
- Pick plants by risk, not rotation alone. Include the one nobody visits.
- Do surprise stock counts at least for high-value items.
- Combine finance and operations skills in the team.
- Spend time on the shop floor. Many issues are visible only there.
- Share findings with plant heads before the head office report.
Frequently Asked Questions
What is the biggest risk in manufacturing internal audit?
Inventory and procurement are the most common high-risk areas, but your own data should decide. Look at write-offs, stock variances and vendor complaints.
Should internal audit attend the physical stock count?
Yes, at least for significant locations. It is the best chance to see the stock and test the count process.
How is this different from a cost audit?
Cost audit is a statutory review of cost records for companies the rules cover. Internal audit is a broader review of controls and risks for the board.
Can the same team audit all plants?
Yes, but rotate people so fresh eyes see each site, and use common test programmes so results compare.
How often should plants be audited?
Set the cycle by risk. See our audit universe guide.
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