Unable to validate Revised Return

Sweety Rego (1 Points)

24 June 2021  

I made a mistake. I filed an ITR-1 earlier today via the new portal, but forgot to fill up the Self Assessment Tax section i.e. the challan 280 details. Happily validated and e-verified the incomplete return.

After realizing my mistake, I tried sending a revised return, only to get an error while submitting. It said the return cannot be validated because "Option for new tax regime u/s 115BAC cannot be opted after due date of filing of return mentioned u/s 139(1)."

Now I had opted for the new tax regime in the original return, and this is for Assessment Year 2021-22, so the due date is far away. I dont understand the error. Website glitch? I dont know what to do next. 

Opting for the old tax regime in the revised form might fix the error, but I'd have to pay a lot more tax. Quite frustrating.