Due date of IT return

1. As per sec 44AD, the partnership firm was included as a part of "assessee" to be included as a part of sec 44AD. Sec 44AD can be opted by the assessee even being a partnership firm and earns income below Rs. 2 crores. 
2. However, on observing sec 44ADA there is no mention "partnership firm as an assessee". 
3. But it is wise to interpret that if a firm is carrying on profession like CA firms they cannot be categorized under sec 44AD and they can only be categorized under sec 44ADA. In that case, Gross receipts or T.O limit will be Rs. 50 lakhs. 
4. Based on the above analogy firm can also carry on business or profession and if it does carry on profession (as specified u/s 44AA) then it will be eligible for sec 44ADA and the limit will be Rs. 50 lakhs. 
5. To answer to your question if the firm is carrying business then the limit for tax audit as per sec 44AB would be Rs 1 crores and if the firm decides to opt for presumptive taxation it can do so. If the firm is carrying on profession then the limit is Rs. 50 lakhs and thus it cannot opt for presumptive taxation and thus tax audit will also be applicable on the same. 
6. To summarise only if the firm is carrying on a business tax audit will not be applicable. If it is carrying on profession then tax audit will be applicable as per sec 44AB. 
7. Individual return is to be filed incorporating salary from the firm and his/her other income from the teaching profession and it should be filed before 31st of August. 
Please correct me if the above interpretation has an alternative view.