Working with Distribution Rules 
A distribution rule is a cost accounting method used to allocate direct and indirect expenses and revenues to one or more cost centers. It contains information regarding the portion of the expenses or revenues to be allocated to each cost center.
Example
To distribute the indirect expenses incurred by rent, you can specify the portion of the total rented space that a specific cost center uses. If one store uses 150 square yards of the total rented floor space of 200 square yards, and the other uses only 50 square yards, you can distribute the expenses incurred by rent and professional cleaning services proportionately between the stores on the basis of the space they occupy. To achieve this, you can assign the distribution rules to the appropriate expense accounts and revenue accounts.
Another way of defining such a distribution rule would involve expressing the number of employees belonging to a cost center as a proportion of the total head count in the company.
You can link distribution rules to respective expenditure and sales G/L accounts of the business. As a result, the amount of each accounting transaction that is posted to these accounts is recorded in the respective cost centers according to the ratio defined in the distribution rules.
SAP Business One provides the following three kinds of distribution rules:
Distribution rules that SAP Business One creates when you create cost centers. This kind of distribution rule has a one-to-one relationship with the corresponding cost centers.
Distribution rules that you create as master data. This kind of distribution rule is the most common one. You create it to allocate direct and indirect expenses and revenues to one or more cost centers.
Distribution rules that you create manually for individual transactions. This kind of distribution rule is defined for particular transactions and does not affect the distribution rule master data.
Authorization is required for viewing and defining distribution rules.
To define distribution rules, choose 
Financials 
Cost Accounting Distribution Rules 
.