section 273A

1 month from the end of month of receipt of order.

(actually query is not properly drafted)

As I said your query itself is not to the mark.

Attachment is for section 273A, where it is mentioned your application can be processed within 12 months, by the authority.

But application is to be made against the order you have received, for which you wish to appeal. There it would have been mentioned the time limit.

Under which section interest is charged?

Refer: reduction-or-waiver-of-income-tax-penalty

As per sec. 256A & 249 of IT act ....   Within 30 days of the date on which intimation of the order sought to be appealed against is served. However CIT (A) may entertain an application even after the expiry of aforesaid period of 30 days

Also refer:: guidelines-for-waiver-of-interest-charged-us-201/1ai-of-the-income-tax-act

Correct typo error.... As per sec. 246A & 249 of IT act .............. .................... .............

Well. I tried my best to give you the exact answer, and there is no different reply to it in Income tax act; but sorry to say.... can't satisfy you.

Good luck.