If you have added the field Internal order in the Asset Master as a statistical order and you want your depreciation
posted not only to the cost center but also to this order. 

In transaction OAYR in the IMG you define how depreciation posts to the depreciation posting rules - there is a CO assignment box where you have to tick both cost centres and internal orders.

What is internal order?  Explain with example and how it is related to cost center.

An internal order is used to accumulate cost for a specific project or task for a specific time period. An internal order is therefore used for a short period with a specific deadline.

Your internal order will usually settle to cost centers (and not visa versa) according to the settlement rule in the order setup.

An internal order can therefore be used to group all the expenses incurred to plan and hold a conference over a 3 month period. The order can be settled on a monthly basis to cost centers. When the conference is finished the order can be settled finally. The cost of the conference will then be spread over 2 or more cost centers, but can be viewed in total on the internal order when needed.

Internal Orders - It is an instrument used to monitor costs and, in some instances, the revenues of an organization.

Uses of Internal orders 
- Monitoring the costs of short-term jobs
- Monitoring the costs and revenues of a specific service
- On going cost control

Internal order categories
- Overhead Orders
- Investment Orders
- Accrual Orders
- Orders with revenue

Cost centers are not for specific job.  e.g If you have open Trade-fair / exhibition (1 month period), then to allocate cost, you can use Internal Orders (Say IO) you can post to IO, and from their to various cost centers. If management were to ask you the cost of that exhibition, Internal Order will help you

Cost center is a responsible center in SAP. It cannot be defined as statistical but in transactions it may become as per other co objects.You will be able to find out the performance of the cost center using activities and plan values with actual value. This is lowest cost object in SAP. This will become a statistical object when you allocate the cost to other higher objects. Cost can be allocated to other cost centers or co objects but not fi objects like GL,assets, inventory etc. can be defaulted in transactions through cost element. It cannot be a cost object for a revenue element, revenues are always taken for other higher CO objects. No budget functionality is available but planning functionality is available and is always measured for a year in business.

Internal order is the second CO object - which can be defined as statistical or real. You will be able to define Budget and planning figures - more than one year also. Can control the postings of FI through budget controls. You can have the report of Plan vs actual including commitment. Cost cannot be allocated but settled through settlement rules and profiles. The receiver of the values can be any object not like Cost center - can be CO objects and FI objects. Ideal for R&D expenses capitalisations, etc. Status profile is linked to this which controls many individual transactions in each status which is a part of this Internal order. It can also receive postings of activities from Cost center. Settlement profile is an wonderful tool for variety of settlement - needed for FI and CO - legal requirements also and Revenue requirements also for any country.

All SAP CO orders like Production order, Plant maintenance order, etc will behave like Internal order with more functinalities.

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