I too encountered the same problem. Can anyone address it. 80TTA deduction not available in ITR3 online filing 

I was having same problem. Filing ITR3. 80 TTA is embedded here inside the income tax website.

Go to Schedule VI-A section

Select Part CA and D

Do you want to add more deductions and Select 80 TTA from the dropdown and get the deduction applied.

Please note - I am not an expert and this is not an advice; please consult a CA for verification.

Thanks! This worked!!