A to Z Costing Knowledge Glossary — Letter I
Investopedia-style costing concepts explained with formulas, practical examples, comparisons, and exam-focused teaching tips.
1 Idle Time
| Category | Labour Costing |
|---|---|
| Best Used In | Payroll accounting, efficiency tracking |
| Key Formula | Idle Time = Time Paid For − Time Actually Worked |
| Exam Importance | Very High |
Idle Time is the period for which workers are paid wages but no production takes place. It is the gap between the time clocked in at the factory gates and the time actually spent working on a job or machine.
It is classified into Normal Idle Time (unavoidable, like walking to the machine, tea breaks) and Abnormal Idle Time (avoidable, like machine breakdown, power failure, or material shortage).
- Inflating the hourly rate of good production (Normal Idle Time)
- Transferring losses to the Costing P&L account (Abnormal Idle Time)
- Performance appraisal of maintenance/procurement teams
A worker is paid for an 8-hour shift. They spend 30 minutes on lunch and transit (Normal) and 2 hours waiting because a machine broke (Abnormal). The cost accountant absorbs the 30 mins into the cost of the products made, but charges the 2-hour wage directly to the P&L as a loss to avoid inflating product prices.
Worker paid ₹100/hr for a 40-hour week (Total Pay = ₹4,000). Normal idle time = 2 hrs. Abnormal idle time (power cut) = 3 hrs. Effective hours worked = 35 hrs.
Treatment: ₹300 (abnormal) is written off to P&L. The remaining ₹3,700 is absorbed over the 38 productive hours (40 – 2 normal), giving an effective labour rate of ₹97.36/hr.
- Record total hours paid (Gate time).
- Subtract Abnormal Idle Time to find Cost of Abnormal Idle Time (transfer to Costing P&L).
- Subtract Normal Idle Time from remaining hours to find Effective Output Hours.
- Divide the remaining wage pool by the Effective Output Hours to find the true cost per hour of production.
| Normal Idle Time vs. Abnormal Idle Time | Normal is absorbed by inflating the wage rate of good units. Abnormal is strictly written off to the Costing P&L so it doesn’t artificially inflate inventory valuation. |
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2 Idle Capacity
| Category | Overhead Costing / Capacity Analysis |
|---|---|
| Best Used In | Fixed overhead variance, strategic planning |
| Key Formula | Idle Capacity = Practical Capacity − Actual Capacity Utilized |
| Exam Importance | High |
Idle Capacity refers to the unutilized productive potential of a factory’s machines or workforce. It represents the difference between the maximum production a plant could reasonably achieve and what it actually produced.
It highlights the sunk cost of fixed assets sitting unused. Like idle time, it is split into Normal (expected downtime for maintenance/seasonality) and Abnormal (unused due to lack of sales orders, strikes, or supply chain failure).
- Pricing decisions (offering discounts to utilize idle capacity)
- Calculating Fixed Overhead Volume Variances
- Evaluating return on capital employed (ROCE)
A bottling plant can produce 100,000 bottles a month (Practical Capacity). Due to a drop in market demand, it only produces 60,000 bottles. The 40,000 unproduced bottles represent Idle Capacity. Management must decide whether to accept a special, low-priced export order to utilize this 40% unused space.
Factory Rent = ₹5,00,000/month. Practical Capacity = 10,000 machine hours. Actual Hours worked = 8,000.
Idle Capacity = 2,000 hours (20%).
Cost of Idle Capacity = 20% × ₹5,00,000 = ₹1,00,000. If this is due to a sudden strike (abnormal), this ₹1L is charged to the Costing P&L, not to the products.
- Determine the Practical Capacity (Max capacity minus normal maintenance/breaks).
- Measure Actual Capacity utilized during the period.
- Find the difference (Idle Capacity).
- Multiply by the predetermined Fixed Overhead Rate to find the financial loss of the unused capacity.
| Idle Capacity vs. Idle Time | Idle time usually refers to labour (workers waiting). Idle capacity usually refers to plant/machinery (machines turned off). |
|---|---|
| Practical vs. Theoretical Capacity | Theoretical is 24/7/365 with zero stops. Practical accounts for unavoidable maintenance and Sundays. |
3 Idle Time Variance
| Category | Standard Costing (Labour Variances) |
|---|---|
| Best Used In | Variance analysis, performance evaluation |
| Key Formula | Abnormal Idle Time Hours × Standard Hourly Rate |
| Exam Importance | High |
Idle Time Variance is a sub-variance of the Labour Efficiency Variance. It calculates the financial loss specifically caused by abnormal idle time (like machine breakdowns or material shortages).
This variance is always Adverse (Negative). It isolates the cost of workers sitting idle, ensuring this specific inefficiency is not mixed up with the workers’ actual performance speed when they were actively working.
- Reconciling total labour cost variance
- Holding the maintenance or procurement department accountable
- Cleaning up the Labour Efficiency Variance calculation
If the total Labour Efficiency Variance is Adverse ₹5,000, management might blame the workers for being slow. However, if Idle Time Variance is calculated at Adverse ₹4,000 (due to a power cut), management knows the workers’ actual working speed was only responsible for ₹1,000 of the loss.
Standard Rate = ₹50/hr. Total Hours Paid = 100 hrs. Machine Breakdown (Idle Time) = 5 hrs. Actual Hours Worked = 95 hrs.
Idle Time Variance = 5 hrs × ₹50 = ₹250 (Adverse).
Note: The remaining efficiency variance will be calculated using 95 hours, not 100.
(Always Adverse)
- Identify the abnormal idle hours recorded from the factory floor.
- Identify the Standard Labour Rate (never use the actual rate for this variance).
- Multiply the hours by the standard rate.
- Label the result as Adverse (A).
| Idle Time Variance vs. Labour Efficiency Variance | Labour Efficiency = (Standard Hours – Actual Hours WORKED) × Std Rate. Idle Time = (Actual Hours PAID – Actual Hours WORKED) × Std Rate. |
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4 Imputed Cost (Notional Cost)
| Category | Decision Making / Cost Concepts |
|---|---|
| Best Used In | Make or Buy decisions, Opportunity cost analysis |
| Key Formula | N/A (Concept-based inclusion in decision models) |
| Exam Importance | High |
Imputed Costs (or Notional Costs) are costs that do not involve actual cash outlays but are recognized for decision-making purposes to reflect the true economic cost of using owned resources.
Because they are not cash transactions, they are never recorded in financial accounting. However, in management accounting, ignoring them would lead to poor decisions (e.g., ignoring the rent you *could* have earned if you didn’t use your own building).
- Evaluating the true profitability of a sole proprietorship
- Comparing self-owned capital projects vs. bank-funded projects
- Make-or-buy decisions utilizing existing factory space
A business owner uses ₹10 Lakhs of their own savings to start a business, instead of taking a bank loan. Financial accounting shows ₹0 interest expense. Cost accounting includes an “Imputed Cost” of ₹70,000 (assuming 7% FD rate) to ensure the business is actually generating a real economic profit, not just eating the owner’s lost interest.
Common Imputed Costs include:
1. Interest on owner’s own capital.
2. Rent for a self-owned building.
3. Salary for an owner-manager who takes no formal paycheck.
- Identify resources used by the firm that it already owns (capital, land, owner’s time).
- Determine the market rate for these resources (FD interest rate, market rent, market salary).
- Include these figures as costs when making internal decisions to find the true economic viability.
| Imputed Cost vs. Out-of-Pocket Cost | Out-of-pocket costs require actual cash leaving the bank. Imputed costs are “invisible” lost opportunities involving zero cash flow. |
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5 Incremental Cost
| Category | Decision Making / Relevant Costing |
|---|---|
| Best Used In | Special orders, expanding capacity |
| Key Formula | Cost of Option B − Cost of Option A |
| Exam Importance | Very High |
Incremental Cost is the additional total cost incurred as a direct result of choosing one alternative over another or increasing the volume of output by a specific batch/amount.
It acts as the cornerstone of short-term decision making. Instead of looking at total average costs (which include irrelevant sunk/fixed costs), managers only look at the extra costs caused by the extra decision.
- Accepting or rejecting a one-time special order
- Adding a new shift or upgrading machinery
- Make-or-buy (outsourcing) decisions
A hotel has 100 rooms. Running 50 rooms costs ₹50,000. Running 51 rooms costs ₹50,200. The incremental cost of renting out one more room is only ₹200 (housekeeping, soap, laundry). The manager can accept a customer offering ₹500 for the room, even if the “average cost” per room is ₹1,000.
Producing 10,000 units costs ₹1,50,000.
Producing 12,000 units costs ₹1,75,000.
Incremental Cost = ₹1,75,000 – ₹1,50,000 = ₹25,000.
If a customer offers ₹30,000 for the extra 2,000 units, the company should accept it, as Incremental Revenue (₹30K) > Incremental Cost (₹25K).
- Calculate the total cost of the business as it operates right now.
- Calculate the total cost of the business if the new decision is taken (including any step-up fixed costs or new variable costs).
- Subtract Current Cost from New Cost.
- Compare this Incremental Cost against the Incremental Revenue generated by the decision.
| Incremental Cost vs. Marginal Cost | Marginal cost is the cost of exactly ONE additional unit. Incremental cost usually refers to a bulk change or a whole decision (like adding a batch of 1,000 units or a new machine). |
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6 Indirect Material
| Category | Cost Elements |
|---|---|
| Best Used In | Overhead classification, Cost Sheet prep |
| Key Formula | Treated as Factory Overhead |
| Exam Importance | Medium |
Indirect Materials are materials used in the manufacturing process that do not become a physical, measurable part of the final product, or are of such little value that tracing them is not cost-effective.
Because they cannot be conveniently linked to a single unit of output, they are classified as part of Factory Overheads rather than Prime Cost, and are absorbed into product costs using an overhead rate.
- Classification of store issues
- Building Factory Overhead pools
- Determining Prime Cost vs Works Cost
In a furniture factory, the wood is Direct Material. The glue, the sandpaper used to smooth the edges, and the grease used to lubricate the cutting machines are Indirect Materials. It is impossible to calculate exactly how much grease is in one chair, so it is treated as an overhead.
A textile manufacturer issues ₹5,00,000 of cotton yarn (Direct Material) and ₹10,000 of machine lubricants and cotton waste for cleaning (Indirect Material).
The ₹5,00,000 goes straight to Prime Cost.
The ₹10,000 goes to Factory Overheads.
- Look at the material requisition slip.
- Ask: “Can I easily and accurately measure how much of this is inside one finished unit?”
- If No (glue, nails, lubricants, cleaning supplies), classify it as Indirect Material.
- Add it to the total Factory Overhead pool for later apportionment.
| Indirect Material vs. Direct Material | Direct material physically forms the primary body of the product and its cost is highly traceable (e.g., steel in a car). Indirect material assists the process but isn’t easily traceable. |
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7 Indirect Labour
| Category | Cost Elements |
|---|---|
| Best Used In | Overhead classification, Cost Sheet prep |
| Key Formula | Treated as Factory Overhead |
| Exam Importance | Medium |
Indirect Labour refers to wages paid to employees who support the production process but do not actually work hands-on to convert raw materials into finished goods.
Because their time cannot be traced to a specific batch or product, their wages are pooled into Factory Overheads and absorbed using a predetermined rate. (Note: Admin staff are Admin Overheads, not Factory).
- Preparing Cost Sheets (Prime Cost vs Overheads)
- Allocating service department costs
- Calculating Factory Overhead Rates
A welder making a steel pipe is Direct Labour. The supervisor watching the welder, the forklift driver moving the steel, and the security guard at the factory gate are all Indirect Labour. Their wages are spread across all the pipes made that day.
Wages paid to machine operators = ₹2,00,000 (Direct Labour → Prime Cost).
Salary of Factory Manager = ₹50,000 (Indirect Labour → Factory Overhead).
Wages of Sweepers in Factory = ₹10,000 (Indirect Labour → Factory Overhead).
Salary of HR Manager = ₹40,000 (Indirect Labour → Office & Admin Overhead).
- Review the payroll sheet.
- Identify employees who do not directly touch or alter the product.
- Classify them based on location: Factory (Supervisor) vs Office (Accountant) vs Sales (Delivery Driver).
- Route their costs to the respective overhead pool.
| Indirect Labour vs. Direct Labour | Direct labour uses hands or tools to physically change the product. Indirect labour organizes, moves, or supervises. |
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8 Indirect Expenses
| Category | Cost Elements |
|---|---|
| Best Used In | Overhead classification |
| Key Formula | Treated as Overheads |
| Exam Importance | Medium |
Indirect Expenses are all costs incurred in the business (other than material and labour) that cannot be directly linked to a specific cost unit or product.
These form the third and final element of overheads. They cover the general running costs of the facility, such as rent, insurance, depreciation, electricity, and advertising.
- Apportionment of shared costs across departments
- Building comprehensive cost pools
- Determining total product cost
You cannot charge the factory’s fire insurance directly to “Batch A” of shoes, because the insurance covers the whole building regardless of what is produced. Therefore, the insurance is an indirect expense, pooled into Factory Overhead, and absorbed per machine hour.
A business pays ₹1,00,000 for electricity.
If ₹20,000 of that is for a specific, metered furnace dedicated to Job X, that ₹20K is a Direct Expense.
The remaining ₹80,000 for general lighting and air conditioning is an Indirect Expense (Overhead).
- Identify expenses that are not material or labour.
- Ask: “Was this expense incurred exclusively for one specific job?” (e.g., hiring a special architect for one client). If yes, it’s Direct.
- If the expense benefits multiple jobs or the whole company (rent, depreciation), it is an Indirect Expense.
- Route to Factory, Admin, or Selling overhead pools based on its nature.
| Indirect Expenses vs. Direct Expenses | Direct expenses (chargeable expenses) are specifically incurred for one job (like a special mold). Indirect expenses are general (like factory rent). |
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9 Input Tax Credit (ITC) Treatment
| Category | Material Costing / Statutory Compliance |
|---|---|
| Best Used In | Valuing material receipts in Store Ledgers |
| Key Formula | Cost = Invoice Price (Exclude GST if ITC available) |
| Exam Importance | Very High |
Input Tax Credit (ITC) is the mechanism in GST where a business can reduce the tax it owes on sales by the amount of tax it already paid on its purchases.
In cost accounting, the core principle is that a recoverable tax is not a cost. Therefore, if ITC is available on a purchase, the GST amount must be completely stripped out of the material cost calculation.
- Calculating accurate Material Cost per unit
- Preparing EOQ and Stores Ledger tables
- Ensuring compliance with CAS-6 (Material Cost)
A car manufacturer buys tires for ₹10,000 + ₹1,800 GST. Since they can claim ITC on the ₹1,800, their accountant values the inventory of tires at exactly ₹10,000. This ensures the final car price isn’t artificially inflated by taxes the company gets refunded.
Purchase of Raw Material: Base Price = ₹50,000. IGST @ 18% = ₹9,000. Total Invoice = ₹59,000.
Case 1: ITC Available → Material Cost recorded = ₹50,000.
Case 2: ITC Blocked (e.g., unregistered dealer) → Material Cost recorded = ₹59,000.
- Look at the total purchase invoice.
- Identify the GST component (CGST, SGST, IGST).
- Read the problem carefully to see if ITC/CENVAT credit is allowed.
- If yes, deduct the tax from the total invoice value to find the pure material cost.
| Recoverable vs. Non-Recoverable Taxes | Recoverable taxes (ITC) are excluded from cost. Non-recoverable taxes (basic customs duty, or blocked ITC) are ADDED to the material cost. |
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10 Integral Accounting System (Integrated Accounts)
| Category | Cost Bookkeeping |
|---|---|
| Best Used In | Modern ERP systems, removing duplication |
| Key Formula | Single set of books (No reconciliation needed) |
| Exam Importance | High |
An Integral (or Integrated) Accounting System is one where both financial accounting and cost accounting transactions are recorded in a single, combined set of books.
In traditional (non-integrated) systems, financial accountants keep one ledger, and cost accountants keep a separate factory ledger, leading to different profit figures that must be reconciled. Integral accounts merge these, eliminating the need for reconciliation.
- Implementation of modern ERP systems (SAP, Oracle)
- Reducing administrative duplication
- Providing real-time profitability tracking
When raw material is purchased on credit, an integrated system immediately debits the “Stores Ledger Control Account” (a costing concept) and credits “Creditors Account” (a financial concept) in one seamless journal entry.
Non-Integrated: Cost books debit Stores Ledger, credit General Ledger Adjustment. Financial books debit Purchases, credit Creditors.
Integrated: Debit Stores Ledger Control A/c. Credit Creditors A/c (One combined entry!).
- Eliminate the “Cost Ledger Control Account” or “General Ledger Adjustment Account” (which acts as a bridge in non-integrated systems).
- Record personal and real accounts (Bank, Debtors, Creditors) directly alongside cost accounts (WIP, Stores).
- Calculate a single, unified Profit & Loss figure.
| Integral vs. Non-Integral Accounting | Non-integral requires two separate sets of books and a Reconciliation Statement. Integral uses one set of books and NO reconciliation. |
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11 Inter-Process Profit
| Category | Process Costing |
|---|---|
| Best Used In | Performance evaluation of sequential departments |
| Key Formula | Transfer Price = Cost of Process + Desired Profit Margin |
| Exam Importance | Very High |
Inter-Process Profit occurs when the output of one manufacturing process is transferred to the next sequential process not at cost, but at a marked-up price (transfer price) that includes a notional profit.
It is used to measure the efficiency and profitability of each individual process department as if they were separate businesses. However, this creates an issue: closing stock will contain “unrealized profit” that must be eliminated for final financial reporting.
- Evaluating managers of specific processes (e.g., Spinning vs Weaving)
- Make-or-buy decisions at intermediate stages
- Responsibility accounting in process industries
A textile mill spins yarn (Process 1) and weaves cloth (Process 2). Yarn costs ₹100/kg to make. Instead of passing it to Process 2 at ₹100, Process 1 passes it at the market price of ₹120. Process 1 shows a ₹20 profit, proving its efficiency. Process 2 is forced to be efficient to make a profit above the ₹120 cost.
Process A Total Cost = ₹1,00,000. Transferred to Process B at Cost + 25% = ₹1,25,000.
Process A reports ₹25,000 profit.
Process B receives goods at ₹1,25,000. If Process B has 10% of these goods in closing stock, that stock is valued at ₹12,500, which includes ₹2,500 of unrealized profit that must be reversed in the balance sheet.
- Calculate total cost of Process 1.
- Add the designated profit percentage to find Transfer Value to Process 2.
- In Process 2, keep three columns in the ledger: Cost, Profit, and Total.
- When calculating Closing Stock in Process 2, use the formula to strip out the “Profit” portion to prevent overvaluing inventory on the balance sheet.
| Inter-Process Profit vs. Normal Process Costing | Normal costing transfers goods at pure cost. Inter-process introduces internal markups to judge departmental efficiency. |
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12 Inventory Control
| Category | Material Costing |
|---|---|
| Best Used In | Supply chain, warehouse management |
| Key Formula | Application of EOQ, Reorder Levels, ABC Analysis |
| Exam Importance | High |
Inventory Control is the systematic process of managing raw materials, WIP, and finished goods to ensure uninterrupted production while minimizing holding costs, ordering costs, and stockouts.
It acts as the balancing mechanism between two financial dangers: tying up too much working capital in excess stock vs. losing sales and stopping production due to stockouts.
- Setting Reorder Levels (When to buy)
- Calculating EOQ (How much to buy)
- ABC Analysis (Prioritizing high-value items)
A car manufacturer applies ABC analysis. The engine (A-class, high value) is tightly controlled with weekly deliveries (JIT) to save holding costs. Nuts and bolts (C-class, low value) are ordered in bulk every 6 months to save ordering costs, as storing them is cheap.
A manager sets a Reorder Level of 500 units. When stock drops to 500, an order is placed for 1,000 units (EOQ). The safety net is the Minimum Level of 200 units to handle delivery delays.
- Categorize inventory based on value and usage (ABC).
- Determine lead times and consumption rates.
- Calculate mathematical levels (Reorder, Minimum, Maximum, Danger).
- Monitor physical stock perpetually to trigger reorders automatically.
| Inventory Control vs. Storekeeping | Storekeeping is the physical receipt and safeguarding of materials. Inventory Control is the financial and strategic management of *how much* to hold. |
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13 Inventory Turnover Ratio
| Category | Material Control / Performance Metrics |
|---|---|
| Best Used In | Identifying slow-moving or obsolete stock |
| Key Formula | COGS ÷ Average Inventory |
| Exam Importance | High |
The Inventory Turnover Ratio measures how many times a company’s inventory is sold and replaced (turned over) over a specific period, usually a year.
A high ratio indicates fast-moving stock and efficient working capital management. A low ratio indicates slow-moving stock, over-purchasing, or obsolete items tying up cash.
- Material control and fast/slow-moving analysis (FSN)
- Working capital optimization
- Evaluating purchasing department efficiency
A grocery store sells milk. It expects an inventory turnover ratio of 365 (replaced daily). If the ratio drops to 100, the milk is sitting on the shelf for 3 days and might spoil. The manager will immediately reduce order quantities.
Material consumed in the year = ₹12,00,000.
Opening Stock = ₹1,50,000; Closing Stock = ₹2,50,000.
Average Stock = (1,50,000 + 2,50,000) / 2 = ₹2,00,000.
Turnover Ratio = 12,00,000 ÷ 2,00,000 = 6 times per year.
Holding Period = 365 days ÷ 6 = 60.8 days (Stock sits for ~2 months before use).
Inventory Holding Period = 365 DaysTurnover Ratio
- Calculate Cost of Material Consumed (Opening + Purchases – Closing).
- Calculate Average Inventory ((Opening + Closing) / 2).
- Divide Consumed by Average to find the Ratio (in “times”).
- Divide 365 by the Ratio to convert it into days (easier for management to understand).
| Turnover Ratio vs. FSN Analysis | The ratio gives the mathematical velocity. FSN (Fast, Slow, Non-moving) categorizes the items based on that mathematical velocity for management action. |
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14 Ideal Standard
| Category | Standard Costing |
|---|---|
| Best Used In | Long-term goal setting, Continuous Improvement (TQM) |
| Key Formula | N/A (Benchmarking concept) |
| Exam Importance | Medium (Theory) |
An Ideal Standard (or Perfection Standard) is a cost or performance benchmark set under perfectly optimal, flawless conditions. It assumes 100% efficiency, zero machine breakdowns, zero waste, and zero idle time.
Because perfection is practically impossible in reality, ideal standards are almost never achieved. They result in constant Adverse variances. They are used for long-term aspiration, not for punishing daily performance.
- Total Quality Management (TQM) environments
- Six Sigma goal setting
- Identifying the absolute theoretical limit of capacity
Toyota might use an Ideal Standard of “Zero Defects” to drive constant engineering improvements. However, for monthly budgeting and employee bonuses, they use a “Normal/Attainable Standard” (e.g., 2% defect rate) so workers don’t get demotivated by impossible targets.
A machine physically takes 60 seconds to punch a hole.
Ideal Standard: 60 units per hour (assumes no worker fatigue or machine jam).
Attainable Standard: 50 units per hour (allows 10 mins/hr for breaks and setup).
Variance analysis for payroll should use the 50 units, not 60.
- Calculate maximum machine speed.
- Assume zero human error, zero sickness, and zero supply delays.
- Use this figure purely for strategic capital expenditure decisions or automation upgrades, not for daily worker evaluation.
| Ideal Standard vs. Attainable (Practical) Standard | Ideal assumes perfection (no breaks). Attainable allows for normal, unavoidable inefficiencies. Attainable is used for costing; Ideal is used for vision. |
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15 Incentive Wage Plans
| Category | Labour Costing |
|---|---|
| Best Used In | Boosting productivity, lowering cost per unit |
| Key Formula | Base Wage + Performance Bonus |
| Exam Importance | Very High |
Incentive Wage Plans are compensation structures designed to motivate workers to produce more than the standard output by linking their pay directly to their performance and efficiency.
These plans balance two things: guaranteeing a minimum living wage for the worker, while driving down the fixed overhead cost per unit for the employer by increasing total volume.
- Labour-intensive manufacturing
- Overcoming slow production rates under flat time-rate systems
- Implementing piece-rate mechanics safely
If workers are paid a flat ₹500/day, they have no reason to work fast. A manager implements an Incentive Plan (like Rowan): “I guarantee you ₹500, but if you finish the 10-hour job in 8 hours, I’ll pay you an extra bonus.” Workers speed up, and the factory makes more goods in less time.
Common Plans:
1. Halsey: 50% of time saved.
2. Rowan: Bonus proportionate to time saved / time allowed.
3. Taylor’s Differential: High piece rate for hitting target, low piece rate for missing it (punitive).
- Establish a fair, time-studied standard (Time Allowed).
- Guarantee a base hourly rate to protect against machine failure.
- Select a mathematical curve (Halsey/Rowan) to share the savings of faster work between the company and the worker.
| Time Rate vs. Incentive Plan | Time rate pays for presence (hours clocked). Incentive plans pay for presence PLUS speed (efficiency). |
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16 Irrelevant Cost
| Category | Decision Making / Relevant Costing |
|---|---|
| Best Used In | Filtering data for management decisions |
| Key Formula | Exclude from Decision Models |
| Exam Importance | High |
Irrelevant Costs are costs that will not change regardless of which management decision is taken. Because they remain exactly the same under all alternatives, they must be ignored in decision-making analysis.
Including irrelevant costs in a decision model (like a Make-or-Buy analysis) often leads to mathematically flawed choices. Examples include Sunk Costs (past costs) and Committed Fixed Costs (general rent).
- Make vs Buy (Outsourcing) decisions
- Keep vs Replace equipment decisions
- Continue vs Shut-down department analysis
You bought a machine for ₹10 Lakhs last year. Today it breaks. Repairing it costs ₹2 Lakhs. Buying a brand new, better machine costs ₹3 Lakhs. The ₹10 Lakhs you already spent is an Irrelevant Cost (Sunk). The decision is strictly between spending ₹2L (repair) or ₹3L (new).
Company considering closing Branch A.
Branch A Sales = ₹5,00,000. Branch Variable Costs = ₹3,00,000.
Allocated Head Office Rent to Branch A = ₹2,50,000.
The allocated rent is an Irrelevant Cost because the Head Office will still pay it even if Branch A closes. The branch makes a ₹2,00,000 contribution, so it should NOT be closed.
- List all costs associated with a business area.
- Ask: “If I choose Option B instead of Option A, will this specific cash flow change?”
- If the cash outflow happens either way (or already happened), cross it off the list.
- Make the financial decision based purely on the remaining (Relevant) costs.
| Irrelevant Cost vs. Relevant Cost | Relevant costs are future cash flows that change depending on the decision (e.g., Avoidable Fixed Costs). Irrelevant costs don’t change. |
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17 Inventory Valuation
| Category | Material Costing / Financial Reporting |
|---|---|
| Best Used In | Balance sheet preparation, closing stock |
| Key Formula | Lower of Cost or Net Realizable Value (NRV) |
| Exam Importance | Very High |
Inventory Valuation is the accounting process of assigning a monetary value to the unsold stock (Raw Material, WIP, Finished Goods) sitting in a warehouse at the end of a financial period.
Governed by strict standards (like Ind AS 2 / AS 2), the golden rule of prudence applies: Inventory is valued at Cost or Net Realizable Value, whichever is lower, to ensure assets are not overstated.
- Finalizing Cost Sheets and COGS calculations
- Balance Sheet asset reporting
- Identifying obsolescence losses
A mobile phone company has 1,000 units of a 2-year-old phone in stock. It cost ₹10,000 to make each one. However, due to new models, they can only sell it for ₹8,000 today. The inventory valuation rule forces the accountant to value the stock at ₹8,000 (NRV) and immediately book a ₹2,000 loss per unit.
Batch X Cost = ₹50,000. Expected Selling Price = ₹60,000. Selling Expenses = ₹5,000.
Net Realizable Value (NRV) = 60,000 – 5,000 = ₹55,000.
Cost (50k) is lower than NRV (55k). Stock is valued at ₹50,000.
NRV = Estimated Selling Price − Estimated Costs of Completion − Estimated Selling Costs
- Determine the Historical Cost (using FIFO or Weighted Average).
- Calculate NRV by estimating what it would sell for today, minus any costs needed to make that sale happen.
- Compare the two. Pick the lowest figure.
- Apply this rule item-by-item, not globally across the whole warehouse.
| Cost vs. NRV Rule Exception | Raw materials are generally not written down below cost if the finished products they will be used in are expected to be sold at or above cost. |
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18 Inter-Departmental Transfer (Reciprocal Service)
| Category | Overhead Apportionment |
|---|---|
| Best Used In | Secondary distribution of overheads |
| Key Formula | Simultaneous Equations / Repeated Distribution Method |
| Exam Importance | Very High |
Inter-Departmental Transfer deals with the complex situation where Service Departments provide services not just to Production Departments, but also to each other (Reciprocal Services).
For example, the Maintenance Dept fixes the boilers in the Power Dept, and the Power Dept provides electricity to the Maintenance Dept. Their costs must be mathematically cross-allocated before they can be finally dumped into the Production Departments.
- Secondary apportionment of overheads
- Finding the true total cost of a service department
- Accurate factory overhead absorption rates
A cost accountant uses the Simultaneous Equation method to solve the cross-billing between the IT department and the HR department, ensuring all support costs eventually flow to the actual manufacturing assembly lines that generate revenue.
Service Dept S1 costs ₹10,000 and serves S2 (20%).
Service Dept S2 costs ₹8,000 and serves S1 (10%).
Simultaneous Equations:
Total S1 = 10,000 + 0.10(S2)
Total S2 = 8,000 + 0.20(S1)
Solving this gives the true cost of each department to distribute to production.
Method 2: Simultaneous Equations (Algebraic substitution)
- Do the Primary Apportionment (direct and shared costs to all depts).
- Set up equations representing the total cost of Service Dept 1 = Own Cost + % received from Service Dept 2.
- Solve for total cost algebraically.
- Apportion that final solved total purely to the Production Departments based on their usage percentages.
| Reciprocal vs. Step-Down Method | Step-Down assumes service flows only one way (S1 serves S2, but S2 does not serve S1). Reciprocal acknowledges the two-way loop. |
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19 Investigation of Variances
| Category | Standard Costing / Management Control |
|---|---|
| Best Used In | Management by Exception |
| Key Formula | Investigate if Variance > Pre-set Tolerance Limit |
| Exam Importance | Medium |
Investigation of Variances is the managerial process of analyzing the root causes of differences between actual costs and standard costs, specifically focusing on whether the variance is controllable or uncontrollable.
Because investigating costs time and money, management does not investigate every tiny deviation. They establish a “Control Chart” or tolerance limit. Variances falling outside this limit trigger a formal investigation for “Assignable Causes.”
- Applying Management by Exception
- Fixing operational inefficiencies (Material waste, slow labour)
- Updating outdated standards if market conditions changed
A factory sets a tolerance of ±5%. If material costs are 2% over budget, the accountant ignores it as random noise. If material costs are 12% over budget, a formal investigation is launched to find out if the supplier raised prices (uncontrollable) or if the cutting machine is wasting fabric (controllable).
Material Price Variance = ₹500 (Adverse). Investigation shows the Purchasing Manager rushed an order overnight via air-freight instead of standard shipping. This is a Controllable assignable cause, and policy changes are made.
- Calculate all standard costing variances at month-end.
- Filter the variances against a materiality threshold (e.g., any variance > ₹10,000 or > 5%).
- For flagged variances, trace back to the source documents.
- Categorize into Controllable (human error, machine fault) vs Uncontrollable (inflation, tax hike).
- Take corrective action on controllable items.
| Assignable Cause vs. Random Cause | Assignable causes have a specific reason (broken blade). Random causes are normal statistical fluctuations (humidity slightly affecting weight). |
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20 Incremental Revenue
| Category | Decision Making / Relevant Costing |
|---|---|
| Best Used In | Special pricing, further processing decisions |
| Key Formula | Revenue of Option B − Revenue of Option A |
| Exam Importance | High |
Incremental Revenue (also called Differential Revenue) is the additional total revenue generated by selecting one specific business alternative over another.
It is always paired directly with Incremental Cost. If the extra money coming in (Incremental Revenue) is greater than the extra money going out (Incremental Cost), the decision is financially sound, regardless of average overall profits.
- Sell “As-Is” vs Process Further (Joint products)
- Accepting bulk orders at a discounted price
- Dropping a product line
A dairy produces raw milk it can sell for ₹40/liter. It can process the milk into cheese, which sells for the equivalent of ₹60 per original liter of milk. The Incremental Revenue of processing further is ₹20. If processing costs ₹15, they should make cheese (Net gain ₹5).
Company produces 1,000 unpainted chairs, selling at ₹500 each (Total ₹5,00,000).
If painted, they sell for ₹650 each (Total ₹6,50,000).
Incremental Revenue = ₹6,50,000 – ₹5,00,000 = ₹1,50,000.
If the incremental cost of painting is ₹1,00,000, paint them! The sunk cost of making the wood chair is irrelevant.
Decision Rule: Proceed if Incremental Revenue > Incremental Cost
- Identify the sales revenue in the current, baseline scenario.
- Identify the total expected sales revenue in the proposed scenario (including any cannibalization of old sales).
- Subtract Baseline from Proposed to find the exact Incremental amount.
- Compare strictly against the specific Incremental Costs of the proposal.
| Incremental Revenue vs. Total Revenue | Total revenue looks at the whole company. Incremental focuses only on the narrow difference caused by a single Y/N decision. |
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