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Fixed Overheads » Cost Variance = Expenditure Variance + Volume Variance  
The Fixed Overhead Cost variance which is the difference between the fixed overhead absorbed and fixed overhead incurred is sub divided into two as fixed overhead expenditure variance and fixed overhead volume variance.
• Mathematical Derivation of the Constituents
Knowing how the cost variance is segregated into expenditure and efficiency may aid your understand and recollection of the formulae.
Where
• Volume Variance
Thus,
Volume variance is the difference between the fixed overhead expenditure that should have been incurred (given by the budgeted fixed overheads) and the fixed overheads absorbed. • Expenditure Variance
Thus,
Expenditure variance is the difference between the fixed overhead expenditure that should have been incurred (given by the budgeted fixed overheads) and the actual fixed overhead expenditure incurred. 
The Formulae » Fixed Overhead Expenditure Variance (FOHExpV)  
The Fixed Overhead Expenditure Variance gives an idea of how much more or less the actual fixed overhead cost incurred is when compared to the budgeted fixed ovehreads. ⇒ Fixed Overhead Expenditure Variance = Budgeted Fixed Overhead Cost Absorbed − Fixed Overhead Cost Incurred

• Bugeted Fixed Overhead Cost  =  Budgeted Output × Budgeted Rate per unit  BFOHC  =  BO × BR/U 

(Or)  =  Budgeted Time × Budgeted Rate per hour  (Or)  =  BT × BR/H 
• Fixed Overhead Cost Incurred  =  Actual Output × Actual Rate per unit  FOHCI  =  AO × AR/U 

(Or)  =  Actual Time × Actual Rate per hour  (Or)  =  AT × AR/H 
» Note
 Time is measured in hours in most cases. It may be in other units also.
 Budgeted Rate/unit ⇒ Budgeted Fixed Overhead Absorption Rate per unit
 Actual Rate/unit ⇒ Actual Fixed Overhead Absorption Rate per unit
 Budgeted Rate/hour ⇒ Budgeted Fixed Overhead Absorption Rate per hour
 Actual Rate/hour ⇒ Actual Fixed Overhead Absorption Rate per hour
• Overheads Absorbed on Unit Rate Basis
» Calculations based on Output (in Units)
FOHExpV  =  BFOHC − FOHCI 

=  (BO × BR/U) − (AO × AR/U) 
» Calculations based on Input (Time in Hours)
FOHExpV  =  BFOHC − FOHCI 

=  (BT × BR/H) − (AT × AR/H) 
• Overheads Absorbed on Time (Hour) Basis
» Calculations based on Input (Time in Hours)
FOHExpV  =  BFOHC − FOHCI 

=  (BT × BR/H) − (AT × AR/H) 
» Calculations based on Output (in Units)
FOHExpV  =  BFOHC − FOHCI 

=  (BO × BR/U) − (AO × AR/U) 
The basis for absorption adopted is not important for the purpose of calculating this variance. If you notice the above formulae, the formula when calculations are based on units as well as the formula when calculations are based on time is the same in both cases.
Since Budgeted Fixed Overhead and Incurred Fixed Overheads are figures that are straight away available in the working table, the formula is the same in all cases if you interpret it in terms of value. FOHExpV = Budgeted Fixed Overhead − Incurred Fixed Overhead 
Fixed Overhead Expenditure Variance » Formula Interpretation  
The variance would be Nil where the Budgeted overhead cost and the incurred overhead cost are the same.
In problem solving it would be convenient interpreting these formulae in terms of value identifiers rather than the factors that are used to derive value. Thus you need to find the absorbed overhead and there are various formulae for finding the absorbed overhead. This is what you need to remember. 
A Problem  
A factory was to budgeted to produce 2,000 units of output @ one unit per 10 hours productive time working for 25 days. Rs. 40,000 of variable overhead cost and Rs. 80,000 of fixed overhead cost were budgeted to be incurred during that period.
The factory worked for 26 days putting in 860 hours work every day and achieved an output of 2,050 units. The expenditure incurred as overheads was Rs. 49,200 as variable overheads and Rs. 86,100 as fixed overheads. What is the variation in total overhead cost on account of a variation in the fixed overhead expenditure? ? This information is provided by the fixed overhead expenditure variance 
Solution » Working Table  
The problem data arranged in a working table:
• Note
This working table gives all the data that would be needed to solve a problem involving all overhead variances. In Calculating only the total overhead cost variance you may not need all that data.
We give it here so that you get accustomed to preparing the working table by the time you complete going through all the overhead variances. 
Solution » Working Notes  
• Working Time» Budgeted Time [BT]
» Actual Time [AT]

Solution [in all Cases]  
• Calculation of Variance

Formulae using Interrelationships among Variances  
• Verification
The interrelationships between variances would also be useful in verifying whether our calculations are correct or not. After calculating the two fixed overhead variances we can verify whether FOHExpV and FOHVolV add up to FOHCV or not. If FOHExpV + FOHVolV = FOHCV we can assume our calculations to be correct.

Author Credit : The Edifier  ... Continued Page O:12 