Why definatination of accountant under income tax act

In the UK ,CIMA is even not allowed to carry out cost audit of ltd co.Do  have answer why?

Because CIMA is not regulatory for audit and acount.

Can I  (CIMA)become a registered auditor and regulated by another body without joining it?

You can become a member of another body, but all have exacting requirements of additional examinations and supervised training in an audit office for a number of years before audit recognition can be given.

CIMA members are allowed to signoff the accounts of companies with turnovers up to GBP5.6m as examiners (not auditors), but not beyond.

External audit is not covered by CIMA's qualification. Any member who wishes to move into this field can only do so by virtue of membership of another more appropriate body.

Please note that none of these bodies will simply reciprocate membership, and that qualification to perform audit usually involves several years' practical experience in an audit firm, as well as taking examinations.

Source:https://www.cimaglobal.com/Members/Members-handbook/FAQs/Can-I-become-a-registered-auditor