BUSN7031 · Management Accounting and Cost Analysis
Overhead Cost Variances & Management Control
This chapter of the BUSN7031 Management Accounting and Cost Analysis guide at the Australian National University takes the over- or under-allocated overhead from standard costing and decomposes it into up to four variances, each pointing at a distinct managerial cause. Variable overhead splits into a spending variance (the rate paid per hour of the allocation base) and an efficiency variance (how efficiently that base was used). Fixed overhead splits into a spending variance (which equals its flexible-budget variance) and a production-volume variance — and, crucially, has no efficiency variance. The four slices always reconcile back to total over/under-allocated overhead, and the whole framework exists so managers can investigate causes, measure performance and benchmark under the university's closed-book, no-formulae-sheet final.
What this chapter covers
- 011. Standard costing for overhead — budgeted rate × standard base allowed for actual output
- 022. Variable-overhead spending variance — the rate leg, on the actual base used
- 033. Variable-overhead efficiency variance — the base-quantity leg, at the budgeted rate
- 044. The three-column framework — Actual · Flexible-on-actual-base · Allocated
- 055. Fixed-overhead spending variance — actual vs budgeted lump sum (= flexible-budget variance)
- 066. Production-volume variance — budgeted lump sum minus fixed overhead allocated; the denominator effect
- 077. Why there is no fixed-overhead efficiency variance, and the four-variance (2×2) map
- 088. Journal entries (U = debit, F = credit) and management control — investigate, measure, benchmark
Four-variance overhead analysis, reconciled to the total
- +1Budgeted rates. Variable-OH rate = 40,000 ÷ 10,000 DLH = $4 per DLH; fixed-OH rate = 60,000 ÷ 10,000 DLH = $6 per DLH.
- +1Standard DLH allowed for actual output. 4,800 units × 2 DLH = 9,600 DLH — the hours the 4,800 units should have taken.
- +1Variable-OH three columns. (1) Actual = $41,000; (2) flexible on the actual base = 9,840 × $4 = $39,360; (3) allocated = 9,600 × $4 = $38,400.
- +1Variable-OH variances. Spending = (1) − (2) = 41,000 − 39,360 = $1,640 U; efficiency = (2) − (3) = 39,360 − 38,400 = $960 U (960 U reflects the extra base hours, at the budgeted rate).
- +1Fixed-OH allocated and spending. Allocated = 9,600 × $6 = $57,600; spending = actual − budgeted lump sum = 58,500 − 60,000 = $1,500 F (this equals the fixed-OH flexible-budget variance).
- +1Production-volume variance. = budgeted lump sum − fixed-OH allocated = 60,000 − 57,600 = $2,400 U. Unfavourable because output 4,800 < the 5,000-unit denominator → capacity under-utilised. There is no fixed-OH efficiency variance.
- +1Reconcile. Total actual OH = 41,000 + 58,500 = $99,500; total allocated = 38,400 + 57,600 = $96,000; total under-allocated = $3,500 U = 1,640 U + 960 U − 1,500 F + 2,400 U ✓.
Key terms
- Variable-overhead spending variance
- (Actual variable-OH rate − budgeted rate) × the actual quantity of the allocation base used. It captures whether the variable-overhead items cost more or less per hour of the base than planned.
- Variable-overhead efficiency variance
- (Actual base used − base allowed for actual output) × the budgeted variable-OH rate. It measures efficiency of the allocation base (e.g. machine- or labour-hours), not thrift in buying overhead items.
- Fixed-overhead spending variance
- Actual fixed overhead − budgeted lump-sum fixed overhead. Because flexed fixed overhead is the same lump sum at any output, this equals the fixed-overhead flexible-budget variance.
- Production-volume variance (PVV)
- Budgeted lump-sum fixed overhead − fixed overhead allocated (budgeted rate × standard base allowed). Also called the denominator-level variance; it is favourable when actual output exceeds the denominator and unfavourable when it falls short.
- Denominator level
- The planned level of output (and its allocation base) used to unitise fixed overhead into a per-hour rate. A lower denominator level produces a higher unit fixed-overhead cost.
- Four-variance analysis
- The full 2×2 split of the overhead variance: {variable spending, variable efficiency} plus {fixed spending, production-volume}. There is no fixed-overhead efficiency variance, so the fixed side has only two members.
- Over/under-allocated overhead
- Total actual overhead minus total overhead allocated. Under-allocated (actual > allocated) is unfavourable; over-allocated (actual < allocated) is favourable. It equals the sum of all four variances.
- Standard base allowed for actual output
- The quantity of the allocation base the units actually produced should have used, at standard (e.g. standard hours per unit × actual units). It anchors both the efficiency and allocated columns.
Overhead Cost Variances & Management Control FAQ
Can AI help me with overhead cost variances?
Yes — ask Sia to walk through any overhead cost variances problem or concept step by step, the way Australian National University tests it. Sia is an AI tutor that explains the three-column variable-overhead framework, the fixed-overhead spending and production-volume variances, and how the four slices reconcile — so you can rebuild the schedule yourself in the closed-book exam. It is a study aid that builds your understanding, not an answer service.
Why is there no fixed-overhead efficiency variance?
Because total fixed overhead is a lump sum within the relevant range — it does not change with how many hours of the allocation base you use. An efficiency variance measures the effect of using more or fewer input hours, but for a cost that does not flex with hours there is nothing to flex. So fixed overhead splits only into a spending variance and a production-volume variance; being asked for a fixed-overhead efficiency variance is a common distractor.
What is the difference between the variable-overhead spending and efficiency variances?
The spending variance is the rate leg: (actual rate − budgeted rate) on the actual base used — did the overhead items cost more per hour than planned? The efficiency variance is the quantity leg: (actual base used − base allowed for actual output) at the budgeted rate — was the allocation base (e.g. machine-hours) used efficiently? A frequent mistake is to describe the efficiency variance as wasteful overhead spending; it is purely about the base quantity.
How do I know whether the production-volume variance is favourable or unfavourable?
Compare actual output to the denominator (planned) level used to set the fixed-overhead rate. Actual output above the denominator means capacity is over-utilised, giving a favourable production-volume variance; actual output below the denominator means idle capacity, giving an unfavourable one. Reversing this sign is one of the most common slips in the topic — and remember a favourable production-volume variance is not automatically good, since it can signal overproduction and excess inventory.
How does this topic appear on the BUSN7031 exam?
Overhead variances are Week 8 material, so they sit inside the cumulative third online quiz (which covers weeks 1-11) and are a strong candidate for one of the four worked problems in the closed-book final. Expect either a full four-variance computation or a targeted part such as computing the production-volume variance. There is no formulae sheet, so you must reproduce the three-column layout and the fixed-overhead lines from memory and label every variance F or U.
What is the fastest way to check my overhead variance answer?
Reconcile the four variances back to the total over/under-allocated overhead: total actual overhead minus total overhead allocated should equal the algebraic sum of the variable spending, variable efficiency, fixed spending and production-volume variances (favourable amounts subtract, unfavourable add). If the tie-out fails, a rate, a standard-hours figure or an F/U sign is wrong. Examiners award method marks for a correct layout even when one number slips, so always show the columns and the reconciliation.
Studying with AI? Sia — free AI accounting tutor works through BUSN7031 step by step.
Exam move
Treat overhead cost variances as a fixed procedure you can reproduce from memory, because the BUSN7031 final is closed-book with no formulae sheet. Drill the sequence until it is automatic: set the budgeted variable- and fixed-overhead rates, find the standard base allowed for actual output, lay out the variable-overhead three columns (Actual, Flexible-on-actual-base, Allocated) to get the spending and efficiency variances, then compute the fixed-overhead spending variance and the production-volume variance — never a fixed-overhead efficiency variance. Label every variance F or U, get the production-volume sign right by comparing actual output to the denominator level, and finish by reconciling all four back to total over/under-allocated overhead. Practise timed problems, self-test the theory MCQs (which overhead has no efficiency variance, what the efficiency variance really measures, why a favourable production-volume variance can be a warning), and ask Sia to generate similar practice questions and check your working step by step.
