In the financial statements of the bank, the $100 in currency would be shown on the balance sheet as an asset of the bank and the deposit account would be shown as a liability owed by the bank to its customer. The bank's financial statement reflects the economic substance of the transaction, which is that the bank has borrowed $100 from its customer and has contractually obliged itself to repay the customer according to the terms of the agreement. These "physical" reserve funds may be held as deposits at the relevant central bank and will receive interest as per monetary policy.