Demand intimation u/s 143(1) ay 2017-18

You can get details in this link...



https://www.hrblock.in/guides/notice-under-section-143-1/

Thank You for the link. It's useful for me...

 

But.,

Can You explain some detailed activity to the said matter...?

the demand may be due to mismatch in Minor head codes and the challan could not be posted due to that. file a rectification application under 154 mentioning the complete details of tax payments.
if you have paid tax after raising of demand , minor head code should be 400. if you have paid tax on or before filing ITR, it should be 300. if there's any mismatch in codes, contact your jurisdictional AO