Indirect manufacturing costs are the production expenses you cannot trace to a single finished product. They keep the factory running for every product at once: factory rent, equipment depreciation, utilities, the salaries of supervisors who oversee the whole floor rather than assembling one item. For most manufacturers, these costs run 15 to 30 percent of total production spending, and both GAAP and the IRS require them to be folded into inventory values rather than expensed outright. Getting them wrong ripples through product pricing, financial statements, and tax filings.
The Traceability Test
The dividing line between direct and indirect costs is traceability. Direct costs attach neatly to a specific product: the steel in a car door, the wages of the welder who joins it. Indirect costs resist assignment to any single unit. You cannot look at a finished widget and say that it used $1.47 worth of the building’s electricity. The electricity powered every machine on the floor, and carving out one widget’s share requires an allocation formula rather than a direct measurement.
Accountants often call these costs “manufacturing overhead” or “factory burden.” Whatever the label, GAAP requires them to be included in the value of inventory on the balance sheet, not simply written off as a period cost. The IRS imposes a parallel requirement through its inventory capitalization rules, so misclassifying these expenses creates problems on both the financial-reporting side and the tax side.
Common Examples
Indirect Labor
Anyone whose work supports production without touching the product counts as indirect labor. Factory supervisors, quality-control inspectors, maintenance technicians, janitorial staff, and plant security all fall here. Their wages, benefits, and payroll taxes get pooled into overhead. This category is often the single largest slice of indirect costs, and it catches people off guard because the workers are physically present on the factory floor.
Indirect Materials
These are supplies the factory consumes that never become part of the finished good. Lubricants for machinery, cleaning solvents, disposable gloves, sandpaper, and welding gas all qualify. A gallon of machine oil keeps an entire production line moving for days across thousands of units, making it impractical to assign its cost to one product. The same logic applies to adhesive tape used in packaging or filters replaced in ventilation systems.
Facility and Equipment
The factory itself generates a steady stream of indirect costs: rent or mortgage payments, property taxes, building insurance, and depreciation on the structure. Equipment depreciation is another major item, recovered through methods such as the Modified Accelerated Cost Recovery System or, for eligible assets, expensed under Section 179 of the Internal Revenue Code.1Internal Revenue Service. Publication 946 (2024), How To Depreciate Property Maintenance contracts for HVAC systems, waste-disposal fees, and fire-suppression inspections round out this category.
Utilities and Technology
Electricity, natural gas, water, and sewer charges for the factory are indirect because they serve every product line running on the floor. As factories become more automated, software costs increasingly belong here as well. Subscriptions for manufacturing execution systems, enterprise resource planning platforms, and production-scheduling tools all support the overall operation. Depreciation on factory computing equipment follows the same classification.
How These Costs Behave When Volume Changes
Knowing what indirect costs are is only half the picture. Managers also need to understand how those costs move when production volume shifts, because the behavior pattern affects budgeting, pricing, and break-even calculations.
Fixed Costs
Fixed indirect costs stay the same whether you produce a thousand units or ten thousand. A factory lease payment, a flat insurance premium, and straight-line depreciation on equipment do not budge when the schedule changes. The per-unit share of these costs drops as volume rises, which is one reason manufacturers chase higher throughput.
Variable Costs
Variable indirect costs track closely with activity. Electricity consumption climbs as more machines run more hours. Lubricants and disposable tooling get used faster during heavier production. Shut the plant down for a week and most variable indirect costs fall close to zero.
Semi-Variable and Step-Fixed Costs
Many factory expenses blend both patterns. A utility bill often includes a flat connection fee plus a usage charge that rises with consumption, so the cost does not move in a clean linear way.
Step-fixed costs behave differently. They hold steady across a range of output, then jump when you cross a threshold. Supervisor salaries are the classic example: one supervisor handles production up to a certain volume, but once you add a second shift, you hire another supervisor and costs leap upward. Between thresholds the cost is flat. Recognizing this pattern prevents you from assuming overhead will scale smoothly with production.
Allocating Indirect Costs to Products
The Predetermined Overhead Rate
Because indirect costs resist direct tracing, accountants use an allocation formula. The most common approach is a predetermined overhead rate, calculated at the start of the fiscal year by dividing estimated total indirect costs by an estimated activity base. That base might be total machine hours, direct labor hours, or direct labor dollars, depending on what drives overhead consumption in your factory.
Say a company estimates $500,000 in overhead for the year and expects to log 10,000 machine hours. The rate is $50 per machine hour. Every unit that passes through a machine then absorbs overhead at that rate: a product requiring two machine hours picks up $100 in allocated overhead. This applied overhead flows into work-in-process inventory as production occurs, so each unit carries a share of the factory’s total indirect spending.
Activity-Based Costing
A single predetermined rate works well when one activity genuinely drives most overhead. In factories with diverse product lines, automated processes, and significant non-volume costs, a blanket rate can distort product costs. A high-volume, simple product may absorb too much overhead, while a low-volume, complex product absorbs too little.
Activity-based costing addresses this by creating multiple cost pools, each tied to a specific activity and its own cost driver. Instead of one rate based on machine hours, you might have separate rates for machine setups, quality inspections, material handling, and maintenance requests. A product that requires frequent setups and heavy inspection absorbs more of those costs, regardless of how many machine hours it uses.
The tradeoff is complexity. Activity-based costing requires more data collection and more accounting effort. For smaller operations where direct labor still dominates the cost structure, a traditional predetermined rate often provides sufficient accuracy. The method makes the most difference in highly automated facilities where overhead is large relative to direct costs.
Reconciling at Year-End
Because the predetermined rate relies on estimates, the overhead applied during the year almost never matches the actual overhead incurred. If applied overhead falls short, you have underapplied overhead, meaning products did not absorb enough cost. If applied overhead exceeds actual spending, you have overapplied overhead.
Most companies close this gap with a simple adjustment to cost of goods sold. Underapplied overhead increases cost of goods sold, and overapplied overhead decreases it. When the variance is large, some firms spread the adjustment across work-in-process, finished goods, and cost of goods sold proportionally. Either way, the point is to make sure the statements reflect what the factory actually spent, not just what the formula predicted.
What the IRS Requires
The IRS does not let manufacturers deduct indirect production costs as current-year expenses. Under Section 263A of the Internal Revenue Code, known as the Uniform Capitalization rules, manufacturers must capitalize both direct costs and the proper share of indirect costs into inventory. Those costs stay in inventory on the balance sheet until the goods are sold, at which point they flow into cost of goods sold and reduce taxable income.2Office of the Law Revision Counsel. 26 U.S. Code 263A – Capitalization and Inclusion in Inventory Costs of Certain Expenses
The indirect costs that must be capitalized broadly mirror what accountants already classify as manufacturing overhead: factory rent, utilities, equipment depreciation, indirect labor, indirect materials, property taxes on the plant, and insurance. Interest costs also require capitalization when the property being produced has a long useful life or an estimated production period exceeding two years.2Office of the Law Revision Counsel. 26 U.S. Code 263A – Capitalization and Inclusion in Inventory Costs of Certain Expenses The federal regulations governing manufacturer inventories detail which indirect costs are includable, and both fixed and variable indirect production costs must be accounted for.3eCFR. 26 CFR 1.471-11 – Inventories of Manufacturers
Small Business Exemption
Not every manufacturer has to deal with UNICAP. If your business has average annual gross receipts of $32,000,000 or less over the prior three tax years, you are exempt from Section 263A for tax years beginning in 2026.4Internal Revenue Service. Revenue Procedure 2025-32 The threshold adjusts for inflation each year. Smaller manufacturers that qualify can use simpler inventory methods and expense certain costs immediately rather than capitalizing them.
Why Accurate Tracking Matters
Getting indirect costs wrong creates problems in two directions. Underallocate overhead and your products look cheaper to make than they actually are. You set prices too low, report fatter margins than reality supports, and eventually wonder where the cash went. Overallocate and you price yourself out of the market or drop product lines that were actually profitable.
On the tax side, the IRS requires manufacturers to substantiate the expenses they claim, and recordkeeping that ties indirect costs to inventory is the foundation of that substantiation.5Internal Revenue Service. Burden of Proof Misstating inventory values flows directly into a misstatement of taxable income, which can trigger penalties and interest. Records that clearly show gross income, deductions, and credits are not just good practice; the IRS explicitly requires them.6Internal Revenue Service. What Kind of Records Should I Keep
Tracking indirect costs also surfaces operational insights. When you see that machine-setup costs represent a disproportionate share of overhead for a particular product line, you can investigate whether batch sizes need adjusting or whether the production sequence is creating unnecessary changeovers. The allocation exercise is accounting work on the surface, but it often becomes the starting point for real manufacturing improvements.