The existing web portal will be shut for six days between June 1-6.
Officials said the new portal will be made more user-friendly.
An order issued by the systems wing of the department on Wednesday said the "transition" from the old portal -- www.incometaxindiaefiling.gov.in -- to the new --www.incometaxgov.in -- will be completed and made operational from June 7.
"In preparation of this launch and for migration activities, the existing portal of the department at www.incometaxindiaefiling.gov.in would not be available for a brief period of six days from June 1 to 6," the order said.