Dental Laboratory Costs: Inventory, Equipment, and Gross-Margin Tracking

Key takeaway: A dental laboratory needs manufacturing records for materials, labor, production overhead, work in process and finished goods. Define gross margin separately from contribution margin, reconcile inventory quantities and values, and distinguish equipment cash payments from depreciation and tax deductions.

This article is part of our guide to industry accounting specialties.

This guide concerns a laboratory that manufactures restorations for dental customers. A dental practice buying outside-lab services has different economics. The practice’s patient collections and outside-lab-fee ratios are not substitutes for the manufacturer’s sales, production costs and inventory records.

Build the cost record around the case and production stage

Use a case identifier, product category, customer, production status and relevant dates to connect materials, technician work, machine activity, outsourced production, delivery, invoices, credits and remakes. Keep customer billing and collections separately identifiable. A billed case, earned revenue and cash received are not necessarily the same event.

Separate raw materials awaiting production, work in process and completed goods not yet sold. A milling machine is equipment used in production; it is not raw-material inventory. Some tools and supplies need classification based on their use and accounting policy rather than their vendor’s label.

Protect the cost record from duplication. A material purchase enters the relevant inventory or supply account; issuing it to a case records consumption or production cost. The later credit-card or vendor payment clears the obligation rather than creating another cost.

Include appropriate production overhead in manufacturing cost

An absorption-cost model includes direct materials, direct production labor and appropriate indirect production costs. Production supervision, factory occupancy and utilities, machine maintenance and production-equipment depreciation can contribute to manufacturing overhead. Marketing and general administrative costs generally are period expenses rather than automatically part of every case’s inventory cost.

Choose a supportable allocation base, such as machine time or production labor hours, for the relevant cost pool. For GAAP reporting, apply the current inventory requirements in Topic 330. The FASB’s published inventory-cost explanation describes allocating fixed production overhead using normal capacity and expensing abnormal idle-capacity or waste costs. Simply dividing all overhead by a very low month’s output can overstate inventory cost.

Keep the tax calculation separate. Treasury Regulation 1.471-11 addresses manufacturers’ absorption costing, while section 263A and other provisions can affect capitalized tax costs. Qualifying small businesses may use alternatives under section 471(c). Eligibility, a permitted method and any required accounting-method change must be evaluated; an internal dashboard does not make that tax choice.

Calculate labor per case using one consistent unit

A loaded production labor rate can include wages, employer payroll taxes and employee benefits attributable to production. Keep nonproduction time and costs distinguishable, and ensure payroll costs included in that rate are not also allocated a second time in overhead.

Illustration: 100 production hours at a $30 loaded hourly rate cost $3,000. If those hours produced 50 comparable completed cases, the labor cost is $3,000 ÷ 50 = $60 per case. The equivalent calculation is 2 hours per case × $30 = $60. Dividing that $60 by 50 again would be an error.

When cases differ materially, use actual or supportable standard time by case type rather than one average across all products. Explain differences between standard and actual time, overtime, downtime and remakes. Update standards when the production process changes.

Reconcile raw materials, work in process and finished goods

A physical count supports quantities, but matching quantities do not establish correct cost of goods sold. Check unit cost, ownership of goods in transit or on consignment, production stage, overhead allocation, damaged or obsolete stock and period cutoff. Investigate count differences without assuming they prove theft.

This separate hypothetical monthly rollforward assumes consistently valued inventory, no losses, returns or other adjustments, and costs assigned under the chosen absorption-cost policy:

The $5,000 material purchase and $8,000 cost of goods sold answer different questions. Unsold production can remain in inventory, while goods sold this month may include costs carried from a prior month. Reconcile each stage to the case records and general ledger rather than treating all purchases as current COGS.

IRS Publication 538 explains inventory identification, valuation, indirect costs and small-business method alternatives. Apply the rules for the tax year and the laboratory’s actual method; tax inventory and management inventory can differ and need a documented reconciliation.

E-Commerce Cost of Goods Sold is covered in more depth in our related article, “E-Commerce Cost of Goods Sold: Reconciling Purchases, Freight, and Inventory.”

Distinguish gross margin, contribution margin and operating profit

Gross profit = recognized revenue − cost of goods sold. Gross margin percentage is gross profit divided by that revenue, multiplied by 100. Under manufacturing absorption costing, COGS includes the appropriate production overhead associated with the goods sold.

Contribution margin = revenue − variable costs. It is a management measure that shows what remains to cover fixed costs and profit. Direct costs are not always all variable, and variable selling or shipping costs may also matter. If a report subtracts only selected direct costs, label it a direct-cost margin and identify its exclusions.

Consider another hypothetical period with $10,000 recognized sales. Assume the $4,000 direct production costs are all the variable costs associated with those sales; there are no other variable costs, and $1,000 of fixed production overhead belongs in their COGS.

The same sales therefore produce a 60% contribution margin and 50% gross margin in this example. These are not industry benchmarks or client results. Compare your laboratory with an external study only after confirming its sample, period, cost definitions and product mix. A percentage quoted without those details may not be comparable.

Record actual cutoff activity and remake costs

At month-end, recognize revenue and costs from the actual work, delivery or acceptance terms, obligations and applicable accounting basis. Under an accrual manufacturing approach, unfinished cases may remain in work in process; work performed can also create obligations before a supplier invoice arrives. Record a supported accrual when required by the facts and policy, not to keep profit steady.

For tax, Publication 538 explains that accrual deductions generally require a fixed liability, a reasonably determinable amount and economic performance, subject to specific rules and exceptions. Cash, accrual and advance-payment rules must be assessed separately from the management report. Label management estimates and retain a reconciliation to the tax return.

Track each remake to the original case, reason, materials, labor, credits, extra shipping and any additional customer charge. A remake can consume resources without generating another sale. Separate normal production experience from unusual waste or process failures when reviewing inventory and period costs.

A pricing allowance for expected remakes helps evaluate a proposed selling price. It does not automatically establish a book liability or tax deduction. Assess any actual warranty obligation under the applicable financial-reporting rules and apply tax timing requirements separately. Keep pricing assumptions, recognized liabilities and actual costs in distinct records.

Connect equipment records to production cost and cash

For each major machine, retain purchase and installation records, identifying information, the date it is ready and available for its intended use, depreciation schedules, repairs, improvements, financing and disposal documents. Distinguish purchase cost, book carrying amount, tax basis and loan balance.

A loan-funded purchase can add equipment and debt without an immediate payment of the full price. Later principal repayments reduce debt; they are not production depreciation. Interest, maintenance and depreciation each need their proper treatment. If depreciation is included in production overhead, avoid deducting the same book depreciation again elsewhere in the margin calculation.

A tax expensing election or accelerated tax deduction does not automatically remove the equipment’s cost from management reporting over its useful life. Model cash requirements, financing and tax consequences separately before a purchase. A deduction is not a reimbursement of the purchase price.

If this raises questions about Dental Equipment Financing, “Dental Equipment Financing: Accounting and Tax Records to Maintain” addresses it directly.

Use a monthly report that leads to specific follow-up

Review revenue and COGS by case category alongside contribution margin where useful, materials usage, labor hours, overhead variances, inventory aging, remake costs, delivery performance and collections. Keep billed revenue and customer cash collections separate so payment delays do not become unexplained margin changes.

Define each operational metric. For example, a remake rate could count original cases requiring at least one remake divided by original cases in the same defined delivery cohort. Counting remake events instead can produce a different result when one case is remade more than once. State the chosen definition and measurement period consistently.

Assign each variance to someone who can explain and act on it. A change may reflect product mix, material prices, labor efficiency, idle equipment, an inventory adjustment or a pricing issue. Review the explanation before changing the price list or posting a correction.

For a laboratory accounting discussion, bring financial statements, sample case-cost records, inventory rollforwards, supplier invoices, equipment and financing schedules, and the current tax method. Confirm the requested review, recurring reporting, tax work and fees in writing.

Frequently asked questions

What belongs in a dental laboratory’s manufacturing cost?

Under an absorption-cost approach, product cost includes direct materials, direct production labor and appropriate allocated production overhead. Track raw materials, work in process and finished goods. Selling and general administrative costs are generally period expenses, while tax inventory rules and small-business exceptions require separate analysis.

Is a 60% direct-cost margin the same as 60% gross margin?

Not necessarily. Gross margin uses cost of goods sold, which can include production overhead. Contribution margin subtracts variable costs. State the costs included and excluded before comparing margins; a direct-cost-only report should not be presented as full manufacturing gross margin.

Does a physical inventory count prove that cost of goods sold is correct?

No. It supports quantities. Valuation also depends on unit costs, ownership, production stage, labor, overhead, cutoff, waste and obsolescence. Reconcile the count to raw-material, work-in-process and finished-goods records and investigate differences.

Can a pricing allowance for remakes be deducted as a reserve?

Not automatically. A pricing assumption is separate from actual remake costs or a recognized warranty obligation. Assess any financial-statement liability under the applicable reporting rules and any tax deduction under the relevant timing and economic-performance requirements.

How do I calculate labor cost per case without dividing twice?

Either multiply total production hours by the loaded hourly rate and divide by the related cases, or multiply hours per case by the loaded hourly rate. If the hours already are per case, do not divide by the case count again.