Annexure against excise duty payment

the company has export as well as domestic sales.

till not the company was giving annexure from excise dempartment for purchase bills. but now they are saying to take input credit in domestic department.

now my question is

whether the company should take input credit or it is advisable to give annexure in all purchase bills?

what is the impact of the same in costing of products?

do we need to include cost of excise in finding out the cost or because we are taking credit, we hv to avoid the same?

Please let me know your views.

thank you.