Indirect materials are the supplies and resources used during production that can’t be traced back to a specific product. Think of the gloves a factory worker wears, the lubricant that keeps a machine running, or the cleaning supplies used on the production floor. These items support manufacturing but never become part of the finished product itself. They’re typically small, inexpensive, and purchased in bulk.
How Indirect Materials Differ From Direct Materials
The core distinction comes down to traceability. Direct materials physically become part of the finished product. The wood in a table, the flour in a loaf of bread, the steel in a car door. You can measure exactly how much goes into each unit and assign the cost directly. If you double production, you roughly double your direct material costs.
Indirect materials work differently. The sandpaper used to smooth that table, the oil that kept the saw running, the tape holding a template together: none of these end up in the product a customer takes home. Because they support production broadly rather than going into individual units, you can’t neatly assign their cost to a single product or batch. Their costs also behave differently. Rather than scaling in lockstep with production volume, indirect material costs tend to be semi-variable or even fixed within certain production ranges. A factory making 500 tables a month might use roughly the same amount of machine lubricant as one making 600.
Common Examples
Indirect materials span a wide range of categories, but they generally fall into a few buckets:
- Safety and protective equipment: gloves, earplugs, hard hats, respirators, full body suits
- Maintenance supplies: spare parts for machinery, air and oil filters for machines and ventilation systems, lubricants
- Consumable tools and fasteners: disposable tools, nails, screws, fittings
- Cleaning supplies: solvents, rags, disinfectants
- Office and adhesive supplies: tape, glue, adhesives
- Equipment rentals: temporary machinery or tools brought in for production support
A useful example from the Corporate Finance Institute: when a furniture manufacturer builds tables, the wood is a direct material. The nails holding the tables together are technically indirect materials. They do end up in the product, but they’re so inexpensive relative to the total cost that tracking them per unit isn’t worth the effort. This is a common gray area. Some materials physically enter the product but are classified as indirect because their individual cost is negligible.
How Indirect Materials Are Accounted For
In cost accounting, indirect materials are classified as part of manufacturing overhead, not as a standalone product cost. Direct materials and direct labor get assigned to specific products based on actual, measurable usage. Indirect materials get pooled together with other overhead costs (like indirect labor, factory rent, and utilities) and then allocated across products using an estimation method.
Common allocation bases include machine hours, labor hours, or total production volume. For instance, if Product A requires twice as many machine hours as Product B, it would absorb twice as much of the overhead pool, including indirect materials. This introduces some estimation into your cost-per-unit calculation, which is why companies periodically review their allocation methods to make sure they reflect reality.
To put the scale in perspective: in one example calculation, a manufacturer’s total product cost of $15,100 broke down as $12,000 in direct materials, $2,000 in direct labor, $100 in indirect materials, $500 in indirect labor, and $500 in other overhead. Indirect materials were less than 1% of total cost. That’s typical. They’re a small slice individually, but across an entire operation they add up.
Tax Treatment of Indirect Materials
The IRS classifies most indirect materials as “materials and supplies,” a category of tangible, non-inventory property used and consumed in your operations. This includes consumables like fuel, lubricants, and water expected to be used up within 12 months, property with an economic useful life of 12 months or less, items costing $200 or less, and components acquired for maintenance or repair.
When you can deduct these costs depends on how significant they are. Incidental materials and supplies, the minor items you keep on hand without tracking consumption (pens, toner, staplers, trash cans), are deductible in the year you pay for them. Non-incidental materials and supplies are deductible in the year you first use or consume them. However, if these costs are tied to property you’re producing or acquiring for resale, capitalization rules under Section 263A may require you to add those costs to the value of the property rather than deducting them immediately.
Managing Indirect Material Inventory
Because indirect materials are low-cost and high-volume, many businesses struggle to track them efficiently. It’s easy to let bins of gloves or boxes of filters go unmonitored until someone realizes they’ve run out. This creates two problems: production disruptions when supplies run short, and wasted money from over-ordering.
One increasingly common solution is vendor managed inventory (VMI), where your supplier takes responsibility for monitoring and restocking your indirect materials. The supplier either sends someone to physically count stock at regular intervals using a mobile scanning app, or installs sensors and weight scales that automatically track levels and trigger reorders when inventory drops below a set threshold. VMI works especially well for what procurement professionals call “C class” items: the low-value, high-hassle supplies that aren’t worth your team’s time to manage closely.
Indirect Materials in Procurement Strategy
In corporate procurement, indirect materials often fall into what’s known as “tail spend,” the long tail of low-value, non-strategic purchases that collectively account for a meaningful chunk of spending but individually don’t get much attention. Tail spend categories typically include maintenance, repair, and operations (MRO) supplies, IT peripherals, and one-off purchases.
The challenge is that because no single purchase is large enough to warrant negotiation or a formal contract, these costs tend to fly under the radar. Companies often have dozens of suppliers providing overlapping indirect materials with no coordinated pricing. Consolidating these purchases, even partially, can reduce costs and simplify operations. That’s why procurement teams increasingly treat indirect material management as its own discipline rather than an afterthought.