form 3cd ,3cb,3ca

Form No. : 3CA

Audit report under section 44AB of the Income-tax Act, 1961 in a case where the accounts of the business or profession of a person have been audited under any other law

Form No. : 3CB

Audit report under section 44AB of the Income-tax Act, 1961, in the case of a person referred to in clause (b) of sub-rule (1) of rule 6G

Form No. : 3CD

Statement of particulars required to be furnished under section 44AB of the Income-tax Act, 1961

1. Form 3CA 
It is to be filed by an organisation whose accounts are required to be audited under any other act other than the IT act. 
Example: Company. Which requires to get its BOA accounts audited by Companies to act and as well as by IT act. 
2. Form 3CB
It is to be filed by an organisation whose accounts are not subjected to audit under any other act except IT act. 
Example: Partnership firm which is not required to audit under the companies act and only required to get its BOA audited under sec 44AB
3. Form 3CD 
It is nothing but a statement and details in the prescribed form. This is common for assessee filing either form 3CA or 3CB.