The I-T Act does not prescribe any specific books of account for business. However, you are expected to maintain your accounts in such a fashion that the net profit of the business can reasonably and easily be arrived at by the department. For companies the books of account are prescribed under the Companies Act. Further the Institute of Charted Accountants has prescribed certain accounting standards for business that are required to be audited by them. The Income Tax department accepts the books of account maintained under these standards.