Interest earned from FCNR Account is taxable in India from asst year 2005-2006. The tax is as per the slab rates of 10/20/30% as the case may be plus surcharge and cess. An NRI can opt for the concessional rate of 20% tax plus surcharge and cess under Chapter X11A of the Act subject to certain conditions. As far as detailed calculations one can visit
http://www.factorm.com/