The income earned on NRI SB account is taxable and you need to pay taxes if it exceeds the taxable limits, as applicable in your case. You may keep in mind the following issues :
1 Your income will be treated as income accrued and arisen in India and you will be assessed accordingly on such income.
2 If you are keeping money in FDRs, there may be TDS on interest on such FDRs. You will need to file IT returns to claim refund, if you don't have taxable income.
3 You also need to have PAN if you are having interest income on SB/FD accounts.
4 You may be covered under Double taxation relief and you can claim the tax paid by you in India as a credit against your tax liability in your country.
5 Amounts transferred from NRI SB accounts to NRE account will have to be backed by a CA certificate about the discharge of your tax liability.