On the technical question whether a legal heir /representative (LR) of a deceased taxpayer is obliged to report immediately death of the assessee or cancel PAN of the diseased the DHC in 42ITR502 held in the negative in the absence of any such statutory requirement in the Act. It is so even today.
However there shall remain an obligation for the LR to file returns and pay taxes as that of the diseased. For this purpose he shall have to take a new PAN as a legal heir or representative, register the same as a legal heir on the income tax e-filing portal and thereupon proceed to file a return of income of the diseased because there is enshrined liability upon him to pay taxes u/s 159 out of property inherited by him