Defining Cost Accounting Methods for G/L Accounts 
SAP Business One provides two cost accounting methods: distribution rules and projects.
SAP Business One provides two types of cost accounting method settings for G/L accounts:
Checking the cost accounting method assignment of G/L accounts
Assigning default cost accounting methods to G/L accounts
Prerequisites
You have defined the required projects in
Administration 
Setup Financials Projects 
.You have defined the required distribution rules in
Financials Cost Accounting Distribution Rules .You have defined the required G/L accounts in
Financials Chart of Accounts .
Procedure
From the SAP Business One Main Menu, choose
Financials Chart of Accounts .The Chart of Accounts window appears.
Select the required G/L account for which you want to define cost accounting methods.
Select the Project checkbox, which sets the G/L account as relevant to project. You can also specify a default project for the account.
For G/L accounts relevant to project, SAP Business One performs actions defined on the Cost Accounting tab of the General Settings window, in
Administration System Initialization General Settings , for postings in which such
G/L accounts are without project assignment.In the Distribution Rule section, select one or more checkboxes to set the G/L account as relevant to distribution rules of corresponding dimensions. You can also specify default distribution rules for corresponding dimensions.
NoteDistribution rule fields are editable only for G/L accounts of type Sales or Expenditure.
End of the note.For G/L accounts relevant to distribution rules, SAP Business One performs actions defined on the Cost Accounting tab of the General Settings window for postings in which such G/L accounts have no distribution rule assigned to the selected dimensions.
In the Chart of Accounts window, choose the Update button.
Note
The cost accounting methods assigned to G/L accounts in this procedure function as the default methods when you post different transactions in SAP Business One. You might have transactions or documents in which you are required to assign different cost accounting methods to a specific account. In such cases, the default cost accounting methods can be changed in most windows.