Is Assessment done 8 years back time barred?

Hi All,

One of my friend got a notice from IT department for paying the tax relating to return of his father,  filed 8 years ago. The assessment was done 8 years ago only. But they are serving the notice now. His father is dead now.

Is it a time barred case? Does my friend have to respond to the notice and pay the tax or just intimate the IT people that its a time barred case.