Under section 18 of the Registration Act 1908, the registration of a will is optional even if it relates to immoveable property.
There is no provision which requires Registration of Will under the Income Tax Act, 1961 including section 159.
It is difficult to understand then on what basis ITD Efiling website seeks a *registered* will for transfer of account of deceased assessee to legal heir.
Should a Memorandum by ICAI / CA Associations be submitted to the CBDT, Minsitry of Finance to provide a facility of *Nomination of legal representative u/s 159* under the Income Tax Act, 1961 for the purpose of transfer of account to such nominee on presentation of Death Certificate of the assessee in the like manner as Nomination provided by Banks & Financial Institutions. This may save a lot of paperwork.