The reciprocal method allocates support-department costs to operating departments by fully recognizing the mutual services provided among all support departments. For example, the reciprocal method fully incorporates the engineering services provided by the Engineering and Production Control Department to the Materials Management Department and the material-handling services provided by the Materials Management Department to the Engineering and Production Control Department.
Exhibit 16-6 presents one way to understand the reciprocal method as an extension of the step-down method. First, Engineering and Production Control Department budgeted costs are allocated to all other departments, including the Materials Management Support Department (Materials Management, 30%; Machining, 50%; Assembly, 20%). The budgeted costs of the Materials Management Department then total from the first-round allocation), as in Exhibit 16-5. The $354,000 is then allocated to all other departments that the Materials Management Department supports, including the Engineering and Production Control Support Department—Engineering and Production Control, 10%; Machining, 20%; and Assembly, 70% (see Exhibit 16-3). The Engineering and Production Control Department budgeted costs that had been brought down to $0 now have $35,400 from the Materials Management Department allocation. Engineering and Production Control Department costs are again reallocated to all other departments (Materials Management, 30%; Machining, 50%; Assembly, 20%) as previously allocated. Now the Materials Management Department budgeted costs that had been brought down to $0 have $10,620 from the Engineering and Production Control Department allocations. Materials Management Department costs are again reallocated to all departments (Engineering and Production Control, 10%; Machining, 20%; and Assembly, 70%) as previously allocated. Successive rounds result in smaller and smaller amounts being allocated to and reallocated from the support departments until eventually all support-department costs are allocated to the Machining Department and the Assembly Department.

Details of the five allocations are as follows:
Budgeted costs before any interdepartment cost allocation
Engineering and production control: $300,000
Materials management: $264,000
Machining department: $329,000
Assembly department: $227,000
Total: $1,120,000
1st Allocation of Engineering and production Control
Engineering and production control: (300,000)
Materials management (3 tenths): 90,000
Machining department (5 tenths): 150,000
Assembly department (2 tenths): 60,000
1st Allocation of Materials Management
Engineering and production control (1 tenth): 35,400
Materials management: (354,000) in parentheses
Machining department (2 tenths): 70,800
Assembly department (7 tenths): 247,800
2nd Allocation of Engineering and production Control
Engineering and production control: (35,400) in parentheses
Materials management (3 tenths): 10,620
Machining department (5 tenths): 17,700
Assembly department (2 tenths): 7,080
2nd Allocation of Materials Management
Engineering and production control (1 tenth): 1,062
Materials management: (10,620) in parentheses
Machining department (2 tenths): 2,124
Assembly department (7 tenths): 7,434
3rd Allocation of Engineering and production Control (3/10,5/10,2/10)
Engineering and production control: (1,062) in parentheses
Materials management (3 tenths): 319
Machining department (5 tenths): 531
Assembly department (2 tenths): 212
3rd Allocation of Materials Management
Engineering and production control (1 tenth): 32
Materials management: (319) in parentheses
Machining department (2 tenths): 63
Assembly department (7 tenths): 224
4th Allocation of Engineering and production Control
Engineering and production control: (32) in parentheses
Materials management (3 tenths): 10
Machining department (5 tenths): 16
Assembly department (2 tenths): 6
4th Allocation of Materials Management
Engineering and production control (1 tenth): 1
Materials management: (10) in parentheses
Machining department (2 tenths): 2
Assembly department (7 tenths): 7
5th Allocation of Engineering and production Control
Engineering and production control: (1) in parentheses
Materials management (3 tenths): 0
Machining department (5 tenths): 1
Assembly department (2 tenths): 0
Total budgeted overhead of operating departments
Engineering and production control: $0
Materials management: $0
Machining department: $570,237
Assembly department: $549.763
Total: $1,120,000
Note: Total support department amounts allocated and reallocated
Engineering and Production Control is equal to $300,000 plus $35,400 plus $1,062 plus $32 + $1 equals $336,495
Materials Management is equal to $354,000 plus $10,620 plus $319 plus $10 equals $364,949
For allocation of engineering and production the base is $120,000 which is the sum of $36,000, $60,000, and $24,000. So, $36,000 divided by $120,000 gives the fraction 3 by 10, $60,000 divided by $120,000 gives the fraction 5 by 10, and $24,000 divided by $120,000 gives the fraction 2 by 10.
For material management the base is 4,000 labor hours which is the sum of 400and 2,800 labor hours. So, 400 divided by 4000 gives the fraction 1 by 10, 800 divided by 4,000 gives the fraction 2 by 10, and 2,800 divided by 4,000 gives the fraction 7 by 10.
An alternative way to implement the reciprocal method is to formulate and solve linear equations. This implementation requires three steps.

The table depicts how the complete reciprocated budgeted costs are allocated. The details of the table are as follows:
1. To engineering and production control department, one-tenth times 364,949 dollars: 36,495 dollars
2. To machining department, two-tenths times 364,949 dollars: 72,990 dollars
3. To assembly department, seven-tenths times 364,949 dollars: 255,464 dollars
4. Total: 364,949 dollars
Exhibit 16-7 presents summary data based on the reciprocal method.

The diagram is divided into two parts support departments, and operating departments.
Support department contains engineering and production control of $336,495 which is the sum of the already existing 300,000 and $36,495 received from materials management.
Support department also materials management of $369,949 which is the sum of the preexisting $264,000 and $100,949 received from engineering and production to the already existing $264,000 to become $369,949.
Operating department contains machining department, which receives $168,247 from engineering and production control and $72,990 from materials management.
Operating department also contains assembly department, which receives $67,299 from engineering and production control $255,464 from materials management.

Details of the spreadsheet are as follows:
Support department
Engineering and Production Control
Budgeted overhead costs before any interdepartment cost allocations: $300,000
Allocation of engineering and production Control: (336,495) in parentheses
Allocation of materials management (one tenth): 36,495
Total budgeted overhead of operating departments: $0
Materials management
Budgeted overhead costs before any interdepartment cost allocations: $264,000
Allocation of engineering and production Control (three tenths): 100,949
Allocation of materials management: (364,949)
Total budgeted overhead of operating departments: $0
Operating Department
Machining:
Budgeted overhead costs before any interdepartment cost allocations: $329,000
Allocation of engineering and production Control (five tenths): 168,247
Allocation of materials management (two tenths): 72,990
Total budgeted overhead of operating departments: $570,237
Assembly:
Budgeted overhead costs before any interdepartment cost allocations: $227,000
Allocation of engineering and production control (two tenths): 67,299
Allocation of materials management (seven tenths): 255,464
Total budgeted overhead of operating departments: $549,763
Total budgeted overhead of operating departments: $1,120,000
Note 1: Base is $120,000 (sum of $36,000, 60,000, and 24,000), so $36,000 divided by $120,000 gives the fraction 3 by 10, $60,000 divided by $120,000 gives the fraction 5 by 10, and $24,000 divided by $120,000 gives the fraction 2 by 10.
Note 2: Base is 4,000 hours (sum of 400, 800, and 2,800), so 400 divided by 4,000 gives the fraction 1 by 10, 800 divided by 4,000 gives the fraction 2 by 10, and2,800 divided by 4,000 gives the fraction 7 by 10.
Robinson’s $701,444 complete reciprocated budgeted costs of the support departments exceed the budgeted amount of $564,000.

The table depicts complete reciprocated budgeted costs, budgeted costs, and the difference for the engineering and production control department and the materials management department, as well as the totals. The details of the table are as follows:
1. Engineering and production control department
2. Materials management department
3. Total
Each support department’s complete reciprocated budgeted cost is greater than the budgeted amount because it takes into account that support costs are allocated to all departments using its services and not just to operating departments. This step ensures that the reciprocal method fully recognizes all interrelationships among support departments, as well as relationships between support and operating departments. The difference between complete reciprocated budgeted costs and budgeted costs for each support department reflects the costs allocated among support departments. The total budgeted costs allocated to the operating departments under the reciprocal method are still only allocated from the Engineering and Production Control Department and allocated from the Materials Management Department, see Exhibit 16-7).