Cost Classification and Behavior: Product vs Period; Direct vs Indirect; Fixed vs Variable; MOH and Job-Order Costing (Chapter 1 Overview)
Cost Classification and Behavior: Product vs Period; Direct vs Indirect; Fixed vs Variable (Chapter 1 Overview)
Core idea: Use cost classifications and behavior to inform decisions
Cost classification: product vs period; direct vs indirect
Cost behavior: fixed vs variable (and the concept of mixed costs to be covered later in the course)
Key application: allocate costs to products/services to understand profitability and pricing
Product costs vs Period costs
Product costs (aka manufacturing costs): costs that are tied to making the product
Included in inventory (on the balance sheet) until the product is sold
Components: Direct Materials (DM), Direct Labor (DL), Manufacturing Overhead (MOH)
All product costs are added to the cost of inventory (and only expensed as Cost of Goods Sold when the product is sold)
Inventory flow example (from transcript):
Raw Materials Inventory: 0% complete (in pristine state, waiting to be put into production)
Work in Process (WIP): costs accumulated as items are being manufactured
Finished Goods Inventory: 100% complete when products are finished and ready for sale
Once sold, costs move to Cost of Goods Sold (COGS)
Period costs: costs that support the business as a whole and are expensed in the period incurred
Examples cited: CEO salary, office supplies, salesperson commissions, advertising, insurance on finished goods warehouses (to be discussed as period costs in the green/blue sections)
Period costs are not tied to the manufacturing process and often ebb and flow with sales activity
Cost object concept (how we decide product vs period, and direct vs indirect): the cost object is what you’re trying to measure costs for (e.g., a product, a department, a project, or a customer). If a cost can be traced to the cost object, it’s direct; otherwise it’s indirect and allocated through MOH.
Direct costs vs Indirect costs
Direct costs: costs easily traceable to the cost object (often a specific product)
Direct Materials (DM): raw materials that become part of the product and can be traced directly (e.g., the engine, steering wheel, stereo in a car; cotton fabric in a polo shirt)
Direct Labor (DL): the labor directly involved in assembling the product (hands-on work)
Note: janitorial staff, supervisors, or other overhead personnel are not direct costs for the product
Indirect costs (Manufacturing Overhead, MOH): costs that cannot be traced easily to a single product
Indirect Materials (e.g., thread, small components, or other tiny materials not cost-effective to track at the unit level)
Indirect Labor (e.g., supervisors, maintenance workers, janitorial staff who support production)
All other manufacturing overhead costs (utilities, depreciation on plant, lease of factory space, etc.)
Summary rule from the lecture: If a cost is not easily traceable to a specific unit of product, it’s typically classified as indirect and included in MOH; if it is traceable to the product, it’s direct
Example discussions from transcript (illustrative):
A car’s steering wheel and engine are DM/DL; thread and rivets are often treated as indirect materials unless they can be traced cost-effectively
Packaging for a detergent (boxes) can be a direct cost to the product if traceable to each unit; otherwise it’s MOH if not easily traceable
Supervisor, maintenance, or factory overhead people are indirect costs; bottleneck: they support production but are not hands-on with a single unit
Fixed vs Variable costs (and the “relevant range” concept)
Variable costs: total cost changes with production/sales volume; cost per unit remains constant
Example: Direct Materials and Direct Labor are typically variable costs: if you build more cars, you need more tires and more labor hours; per tire cost stays the same
Math: If per-unit variable cost is v and quantity is Q, then total variable cost = , with unit cost v constant
Fixed costs: total cost remains constant within the relevant range; cost per unit changes as volume changes
Example: Rent for a factory: total rent remains the same within a given capacity/time period, so per-unit cost decreases as more units are produced
Concept of relevant range: fixed costs are fixed for the period of interest or for the production capacity being considered; if you expand beyond this range, fixed costs might “reset” to a new level
The transcript’s car example for fixed costs: If rent is $30,000 for 1,000 sq ft, fixed cost per period is constant within the period; as production volume increases, per-unit fixed cost declines (e.g., $30,000 / 1 car vs. $30,000 / 10 cars vs. $30,000 / 30,000 cars)
Important nuance: fixed costs can change over longer horizons (salaries may change, policy renewals, etc.), but for the period under analysis they are fixed
Mixed costs: contain both fixed and variable components (to be discussed in Chapter 6/Chapter 8)
Examples discussed in the lecture:
Direct materials and direct labor are usually variable costs (by unit basis, not necessarily per hour, but total varies with volume)
Rent and depreciation are often fixed costs within the relevant range (per unit declines with more output)
Insurance on a factory or finished goods warehouse is typically fixed within a policy period (not directly tied to volume, though it may change if the space/coverage changes)
Advertising costs are typically period costs; typically treated as fixed with respect to volume (though some relationships can be inverse if marketing spend responds to sales, it is not a direct, proportional relationship to units sold)
Depreciation: not directly tied to units produced or sold; does not have a direct relationship to volume; generally treated as fixed
Quick rules the instructor emphasized:
Variable costs change in total with volume; per-unit cost stays the same
Fixed costs stay the same in total within the relevant range; per-unit cost falls as volume rises
A cost can be product or period; its behavior (fixed vs variable) is described with respect to volume changes
Period costs include selling and administrative costs; product costs include DM, DL, MOH
Manufacturing overhead (MOH) and job order costing (Chapter 2/3 preview)
Manufacturing Overhead (MOH): all production costs not direct materials or direct labor
Broadly categorized into: indirect materials, indirect labor, and everything else (the “other” MOH costs)
MOH must be allocated to individual jobs since it cannot be traced directly to a specific unit
Job order costing (for customized products/services): used when products or services are unique and tracked by job
Direct Materials (DM) and Direct Labor (DL) can be traced to each job
MOH is allocated to jobs using an allocation base and a predetermined overhead rate (POHR)
Allocation bases (three common options):
Allocation Base 1: Machine hours (MH) – for highly automated environments
Allocation Base 2: Direct labor hours (DLH) – for labor-intensive environments with skilled labor
Allocation Base 3: Direct labor dollars (DL$) – when labor costs vary and are a natural driver
Predetermined Overhead Rate (POHR): a rate established at the beginning of the period to apply MOH to jobs
Formula (primary one you should know):
MOH allocated to a specific job:
If using direct labor hours as the base:
If using machine hours as the base:
Why use a POHR?
Smoothing: many companies don’t know exact MOH until the year is over; POHR helps allocate MOH evenly across periods
Stabilizes monthly fluctuations due to seasonality or production variability
All three bases are used in different contexts depending on the company’s production process
Key elements in job order costing
Direct materials and direct labor are traced to each job
MOH is allocated using the POHR and the job’s allocation base
The total cost of a job is the sum of: DM + DL + MOH allocated
The pricing decision for jobs (or products) often relies on this cost-plus approach to ensure overhead and period costs are covered in the price
Inventory accounting and cost flow concepts
Inventory is recorded at all costs necessary to acquire, produce, and ready for sale
Typical flow (as highlighted by the lecture):
Raw Materials Inventory (0% complete)
Work in Process (WIP) – costs accumulate as products are in production
Finished Goods Inventory (100% complete)
Cost of Goods Sold (COGS) when the product is sold
Cost object and cost tracing
The choice of cost object (product, department, project) determines whether a cost is direct or indirect
Depreciation discussion
The depreciation method does not use units produced or units sold as its denominator; it is generally fixed relative to the time period, not volume
Examples and practical applications discussed in the lecture
Car manufacturing example
Direct materials: engine, steering wheel, stereo, etc. are DM
Direct labor: workers assembling the car are DL
Indirect costs: overhead such as supervisors, maintenance staff, and the factory not directly traced to a single car
Packaging example (detergent):
Packaging boxes can be a direct cost if traceable to each unit; otherwise, packaging costs could be treated as MOH
Small-cost items (thread/yarn) discussion
If the cost of tracing a minor component (like thread) is higher than the benefit of tracking it, treat it as indirect
The rule: if tracking a cost would cost more than the benefit, it is treated as indirect
Yarn used in sweater production
Yarn is a direct material (DM) and a product cost; discussed as an example of DM and cementing the idea that primary materials are directly traceable
Administrative vs manufacturing costs (example: yarn, executives, receptionist)
Yarn as product cost (DM) with variable behavior; executives and receptionist are considered period costs with more ambiguous behavior depending on the cost object
Advertising costs
Classified as period costs; typically fixed with respect to volume in the short term; however, advertising spend can respond to sales signals, potentially making it non-linear with volume in practice
Finished goods warehouse insurance
Period cost; usually fixed with respect to volume; depends on policy period and warehouse size; not a direct or indirect cost of production
Connections to broader context and real-world relevance
Chapter 2 and Chapter 3 focus: manufacturing entities that actually make what they sell
Process costing vs. job order costing: this lecture sets up the job order costing framework for customized products/services
Examples of job order costing applications: Boeing (custom airplanes), construction (skyscrapers vs schools), Vistaprint (customized orders)
Why job order costing matters
Allows tracing of direct costs to each job and an allocation of MOH to each job
Supports pricing decisions: ensure costs are covered and margins are adequate through proper markup and cost control
Ethical and practical implications
Accurate cost allocation is crucial for fair pricing, profitability assessment, and compliance with accounting standards
Over- or under-allocating MOH can distort product costs and lead to poor business decisions
Quick recap of key formulas and concepts to memorize
Product vs Period costs
Product costs = Direct Materials + Direct Labor + MOH
Period costs = Selling & Administrative expenses
Direct vs Indirect costs
Direct costs can be traced to a cost object (product)
Indirect costs cannot be traced easily and are allocated as MOH
Variable vs Fixed costs (and mixed costs)
Total Variable Cost = v × Q; per-unit variable cost v is constant
Total Fixed Cost = F (within the relevant range); per-unit cost = F / Q
MOH and allocation in Job Order Costing
MOH = Fixed MOH + Variable MOH
POHR = Total Estimated MOH / Allocation Base
MOH allocated to a job = POHR × Allocation Base for the job
Allocation bases example: machine hours, direct labor hours, direct labor dollars
Inventory flow and COGS timing
Raw materials → WIP → Finished Goods → COGS upon sale
Contextual understanding of relevant range
Fixed costs are fixed within the relevant range; outside that range, re-evaluation may be needed
Cost object focus
The choice of cost object determines how costs are categorized and allocated
Preview of what’s next (Chapter 2/3 focus)
Deep dive into job order costing in manufacturing and service environments
How to apply the MOH allocation process in varied industries
Practice with demonstration problems to identify product vs period, and fixed vs variable costs, and to apply POHR for cost allocation