How to get basic ?

You can calculate discount for your basic price.

For example.

Basic price - 100

discount - 10

after dicount-90

cal Excise for 90  is 9.00 (excise 10%)

for this method u can save 10% of your discount amount. because excise is not l;evy for discount

I agree with u sir, it is general procedure in everywhere, but in this case , our Buyer is calculatiing after payment of Excise duty, (ex:100+10.3=110.3 - disc) he is giving discount , thats why I am asking is there any procedure/calc , without disturbing excise amount , to get BASIC PRICE.

the discount is offered to you eiother cash discount or quantity discount 

so the Excise duty would be chargable on MRP

reduce the discount direct from the basic price