Dear Umeshkumar Jhawar Ji,
Assuming the manufacturing and the usage of finished goods are by same entity (i.e same GSTN) then,
1. ITC shall not be eligible for goods used for manufacturing of finished goods used for consumption for factory building; Pls find section 17(5):-
(5) Notwithstanding anything contained in sub-section (1) of section 16 and subsection (1) of section 18, input tax credit shall not be available in respect of the following, namely:-
(d) goods or services or both received by a taxable person for construction of an immovable property (other than plant or machinery) on his own account including when such goods or services or both are used in the course or furtherance of business.
2. ITC shall be eligible for goods used for manufacturing of finished goods used for consumption for factory building; Pls find explanation which reads as:
Explanation.–– For the purposes of this Chapter and Chapter VI, the expression “plant and machinery” means apparatus, equipment, and machinery fixed to earth by foundation or structural support that are used for making outward supply of goods or services or both and includes such foundation and structural supports but excludes-
(i) land, building or any other civil structures;
(ii) telecommunication towers; and
(iii) pipelines laid outside the factory premises.
So ITC of TMT bars used for foundation / structural support of plant and machinery shall also be available.
3. No requirement for raising self-invoice under the present situation or declaration in GSTR-1 or GSTR-3B return as there is no supply at all;
Subsidiary questions:-
4. The manufacturing expenses such as materials, labour, overheads etc... shall be capitalized either under factory building or under P&M respectively.