According to Sec 44AD(5) an eligible assessee who claims that his profits and gains from the eligible business are lower than the profits and gains specified in sub-section (1) and whose total income exceeds the maximum amount which is not chargeable to income-tax, shall be required to keep and maintain such books of account and other documents as required under sub-section (2) of section 44AA and get them audited and furnish a report of such audit as required under section 44AB."
So according to Sec 44AD(5) yes it is mandatory to do so if his income will exceeding tacxable limits