@KrishnaAgarwal Hi,
Form 27C declaration shall be furnished in duplicate to the person who is responsible to collect tax (i.e Seller.) Then, seller shall deliver to the Chief Commissioner or Commissioner, one copy of the declaration referred to on or before the seventh day of the month next following the month in which the declaration is furnished to the seller.
Here are some of the tax provisions to keep in mind along with declaration of Form-27C:
I hope, it will suffice to you!