Hi Vybhava,
To a given company code you can assing a maximum of three COA's. The chart used for daily postings in your company code would be your operational COA; besides this, you can use two additional COA that could cover the functions of "group COA" (i.e. containing the G/L accounts that are used by the entire corporate group and can provide you with reports at corporate level) or "country-specific COA" (contains the G/L accounts needed to meet a specific country's legal requirements).
In anycase, you will allways need an usable operational COA.
Regards,
Horatiu