A COA must be assigned to a company code. This COA is the operative COA and is used in both FI and CO. One Chart of Account can be assigned to many Company codes i.e., Multiple company codes can either share the same or have separate COA. But a company code (Country specific Company code or International Company code) can have a country specific COA also along with Operative COA. The link between the regular COA and the country COA appears in the alternate number field of the G/L master record.
Eg: If a company's subsidiaries are located in both US & Mexico. We need to configure 2 Company codes - one for US and another for Mexico, for eg U100 and M100. The same way we create 2 COA's one for US & one for Mexico, USCA and MXCA. Mexico has different government reporting requirements than the US so we will need to define a company code specific to Country Mexico and also create a country specific COA to be used, in addition to normal COA. In T-code OBY6(Comp Code Global Parameters) of CC M100 we define normal COA i.e.,USCA in Chart of Accounts field and MXCA in Country Chart/Accts field.