Step 1: Understand Seigniorage.
Seigniorage refers to the profit made by a government through the issuance of currency. This is the difference between the value of money and the cost to produce and distribute it. Seigniorage typically increases the money supply, which can lead to inflation.
Step 2: Evaluate each option.
Option (A): Correct, seigniorage results in an increase in the money supply as the government prints more currency.
Option (B): Correct, by increasing the money supply, seigniorage can lead to inflation as more money chases the same amount of goods.
Option (C): Incorrect, seigniorage does not directly affect the tax rate.
Option (D): Incorrect, while inflation from seigniorage may impact interest rates, seigniorage itself does not directly impact interest rates.
Thus, the correct answer is (A) and (B).