Self assessment tax and return filing

Self assessment tax have to be paid before filing of return and the details of payment have to be filled in the Return. If return is filed without filling the details of tax payable it will be treated as a defective return. 

Got it but doubt not cleared.

E.g- A person paid his self assessment tax in sept of AY and filed the return in march of AY to avoid sec 234A. He paid self assessment tax on the basis of his own assumption. What would be the final effect on his return ?

If the return is filed during the Assessment year, then penalty can not be filed. There is no problem in your case if you do not have carried forward losses. 

no impact, if the self assessment tax is paid within the return due date

as the self assessment tax is paid after the finaicial year close , and its paid before filing the ITR, 

however return filing delay is there 

yes you catch my point