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Microlesson · 5-min read

Idle Time – Definition, Causes, and Accounting Treatment

# Idle Time

## Definition

Idle Time = Time for which payment is made but no production occurs.

> Arises only under a time-based payment system (not under piece-rate).

Formula:

> Idle Time = Time on Time Card − Time booked on Job Card

> Idle Time = Normal Idle Time + Abnormal Idle Time

---

## Normal Idle Time (Unavoidable)

Loss of time that cannot be avoided in the normal course of operations.

Causes:

1. Time lost travelling from factory gate to workstation

2. Machine set-up time

3. Normal fatigue

Sub-classification:

TypeExamples
Normal & ControllableMachine breakdown, waiting for work / tools / materials
Normal & UncontrollableSet-up time, interval between two jobs, normal fatigue

---

## Abnormal Idle Time (Avoidable)

Loss of time that should not occur and can be avoided with proper management.

Causes:

1. Power failure, machine breakdown

2. Non-availability of raw materials

3. Strikes, lockouts

Sub-classification:

TypeExamples
Abnormal & ControllableTime that productive use was possible if management had been alert
Abnormal & UncontrollableTime lost to abnormal causes beyond management control

---

## Accounting Treatment

Type of Idle TimeTreatment in Cost Accounts
Normal & ControllableCharged to Overhead Cost
Normal & UncontrollableCharged to the job by inflating the wage rate per unit
Abnormal Idle TimeCharged to Costing Profit & Loss Account

Worked example

### Example 1

Q: A worker is paid for 8 hours. He spends 30 min walking to workstation, 20 min in machine setup, and 1 hour waiting for materials (which ran out due to poor planning). Rest of time is productive. Classify and treat the idle time.

A:

  • Walking to workstation: 30 min → Normal & Uncontrollable → Inflate wage rate for the job
  • Machine setup: 20 min → Normal & Uncontrollable → Inflate wage rate for the job
  • Waiting for materials (poor planning): 60 min → Normal & Controllable → Charge to Overhead Cost

Total idle time = 110 min. Productive time = 8 × 60 − 110 = 370 min.

⚠️ Common exam mistakes

  • Thinking idle time arises under piece-rate systems — it only arises under time-based payment systems because under piece-rate, unproductive time means zero wages.
  • Treating ALL normal idle time the same way — normal controllable goes to overheads; normal uncontrollable is absorbed into the job by inflating the wage rate.
  • Confusing abnormal idle time treatment: it is NOT charged to overheads or jobs — it goes directly to Costing P&L Account as a loss.
  • Stating machine breakdown always causes 'abnormal' idle time — machine breakdown can be both normal (expected wear) and abnormal (sudden failure).
Reference:
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