here is the way to understand what is DSC

In our example, when the wholesaler buys from the manu- Actual Liability
facturer, he pays a 10% tax on his cost price because the
liability has been passed on to him. Then he adds value
of INR 40 on his cost price of INR 100 and this brings up his
cost to INR 140. Now he has to pay 10% of this price to the
government as tax. But he has already paid one tax to the
manufacturer. So this time what he does is, instead of paying
INR (10% of 140=) 14 to the government as tax, he subtracts
the amount he has paid already. So he deducts the INR 10
he paid on his purchase from his new liability of INR 14, and
pays only INR 4 to the government. So the INR 10 becomes
his input credit.
When he pays INR 4 to the government, he can pass on its liability
to the retailer. So, the retailer pays INR (140+14=) 154
to him to buy the shirt. At the next stage, the retailer adds
value of INR 30 to his cost price and has to pay a 10% tax on
it to the government. When he adds value, his price becomes
INR 170. Now, if he had to pay 10% tax on it, he would pass
on the liability to the customer. But he already has input
credit because he has paid INR 14 to the wholesaler as the
latter’s tax. So, now he reduces INR 14 from his tax liability
of INR (10% of 170=) 17 and has to pay only INR 3 to the
government. And therefore, he can now sell the shirt for INR
(140+30+17) 187 to the customer.
In the end, every time an individual was able to claim input
tax credit, the sale price for him reduced and the cost
price for the person buying his product reduced because
of a lower tax liability. The final value of the shirt also
therefore reduced from INR 214.5 to INR 187, thus reducing
the tax burden on the final customer.
So essentially, GST is going to have a two-pronged benefit.
One, it will reduce the cascading effect of taxes, and second,
by allowing input tax credit, it will reduce the burden of taxes
and, hopefully, prices.