Well the tax Assistant post come under the SSC CGL exam and there is common procedure of the CGL posts

Yes there will bean interview\w for the Tax Assistant post

Selection Criteria

CGL Tier 1:

First of all CGL tier 1 exam will be organised for all candidates. Tier 1 will
be organised for the sake of larger no of applicants.

CGL tier 2:

Graduate level mains exam is also known as TIER II exam. Questions will be
of objective type.

CGL Tier 3:

This tier is also called personality test or interview test i.e.. CPT test/skill
test/document verification and other test will be organised as per as demand of various different post