Overhead absorption explained: this guide covers what it means, who it applies to, the step-by-step process, documents required, fees, due dates and penalties in India — so you can stay compliant with confidence and avoid costly mistakes.
Overheads cannot be traced to a single job, yet a job quote that ignores them loses money. An absorption rate turns a pool of overhead into a rate per hour, per rupee of wages or per unit, so every job picks up its share. For a workshop built around machines, the machine hour rate is the fairest such rate.
Overhead absorption rate = budgeted overhead ÷ budgeted base (machine hours, labour hours, direct wages, material cost or units). Charge each job at the predetermined rate × its base. At the year end, absorbed overhead is compared with actual overhead; the gap is under-absorption (absorbed less than actual) or over-absorption (absorbed more). Use a machine hour rate where machines drive cost, and treat the gap as a signal about spending and utilisation.
What it answers and the data you need
The question is "what overhead should this job carry?" You need the overhead budget for the year (after department apportionment, see the guide on overhead apportionment), a realistic estimate of the base (hours the machine will actually run), and at year end the actual overhead and actual hours. Owners who want a rate card built for their quotations can ask for a costing and pricing analysis.
Choosing a base
| Base | Rate formula | Where it fits |
|---|---|---|
| Direct material cost | Overhead ÷ direct material cost | Material-heavy work with steady prices |
| Direct labour cost | Overhead ÷ direct wages | Labour-driven work with similar wage rates |
| Direct labour hours | Overhead ÷ labour hours | Labour-driven work with different wage rates |
| Machine hours | Overhead ÷ machine hours | Machine-driven work |
| Units | Overhead ÷ units | One uniform product |
A blanket rate averages the whole factory; a departmental rate uses one rate per department. Use departmental rates where jobs use departments differently. A predetermined (budgeted) rate is fixed before the year so quotes can be given; an actual rate is known only at year end and swings with volume.
The machine hour rate
Machine hour rate = (annual machine-related overheads) ÷ (expected productive machine hours). Machine-related overheads include depreciation, power for running, repairs and maintenance, consumables, insurance and the machine's share of rent. Expected productive hours exclude set-up, planned maintenance and idle time. The operator's wage is treated separately, as direct labour, or included if one operator runs one machine all year.
Capacity terms. Full capacity is the theoretical maximum; practical capacity allows for breaks and servicing; normal capacity is the average utilisation over a few years; budgeted capacity is next year's expected level. Dividing by a lower capacity gives a higher rate, so choose the level consciously.
Worked example: an engineering workshop with one CNC machine
Annual budget (all assumed):
| Machine overhead | ₹ |
|---|---|
| Depreciation | 300,000 |
| Power for running | 192,000 |
| Repairs and maintenance | 72,000 |
| Consumables | 36,000 |
| Insurance | 12,000 |
| Share of floor rent | 60,000 |
| Total | 672,000 |
Available hours: 2,400 (8 hours × 25 days × 12 months). After set-up and servicing, expected productive hours = 2,100.
Machine hour rate = 672,000 ÷ 2,100 = ₹320 per hour.
A job needing 5 machine hours carries 5 × 320 = ₹1,600 of machine overhead (plus its material, wages and other costs).
Year-end position (actual). Actual machine overhead ₹690,000; actual machine hours 2,000.
- Overhead absorbed = 2,000 × 320 = 640,000.
- Under-absorbed overhead = 690,000 − 640,000 = ₹50,000.
Why? Split it:
- Spending: 690,000 − 672,000 = 18,000 more than budget.
- Volume: (2,100 − 2,000) × 320 = 32,000 of overhead that the lost 100 hours would have recovered.
- Total 18,000 + 32,000 = 50,000, which agrees with the gap above.
Treating under- and over-absorbed overhead
If the gap is small and arises from ordinary variation, write it off to the costing profit and loss account for the period. If it is large because of a genuine error in the rate, spread it over work in progress, finished goods and cost of goods sold in proportion to the overhead absorbed in each. An abnormal item, such as a long machine breakdown, is better written off, because loading it onto products would make them appear costlier than they should be.
Here the owner would conclude: of ₹50,000 under-recovered, ₹32,000 reflects idle capacity (a sales or planning issue, not a cost of the product) and ₹18,000 reflects overspending (a control issue). The ₹320 rate itself should be revisited only if 2,100 hours was too hopeful. For next year, if sales support only 2,000 hours, a rate on that basis would be 672,000 ÷ 2,000 = ₹336 per hour; quote at ₹320 only if you are confident of reaching 2,100 hours.
Common mistakes
- Dividing by available hours instead of productive hours, which understates the rate.
- Including the operator's wage in the rate and again as direct labour.
- Using a factory-wide rate when one department is machine-heavy and another is manual.
- Ignoring the gap: persistent under-absorption means quotes are too low.
- Using a rate based on the actual month's volume, which makes the quote higher in slack months and lower in busy ones.
The rate flows into the job cost sheet and the standard overhead variances, which look at the same split in a standard costing setting.
Need help with setting overhead rates?
If quotes are made on a rule of thumb, we can help build department-wise rates from your own accounts and test them against past jobs through a costing and pricing analysis.
Key takeaways
- Absorption rate = budgeted overhead ÷ budgeted base; use a predetermined rate.
- A machine hour rate suits machine-driven work: overhead ÷ expected productive machine hours.
- Under-absorption = actual overhead − absorbed overhead (absorbed < actual); over-absorption is the reverse.
- Split the gap into a spending part and a volume part.
- Write off small or abnormal gaps; spread large, rate-related gaps over stock and cost of sales.
Read next
- Job costing: the job cost sheet and pricing a customer order
- Overhead variances: expenditure, volume and efficiency
- Overhead allocation, apportionment and re-apportionment
Disclaimer: The methods described are standard cost accounting and financial management techniques. The worked example uses an invented business and invented figures, including any tax, interest or exchange rate, which are assumptions for illustration and not current rates. Where the article refers to a legal requirement, the linked guide and the official text should be checked. This article is general information, not legal advice; check the official text before acting.