I am referring to liabilities instead of cash because cash is not the only form of legal tender. There are also reserves. Reserves are accounts held by banks with the Central Bank. When a bank needs to pay another bank, it does so by using its accounts with the Central Bank. Payments done in this way are final as well.
Economists refer to the sum of reserves and cash as base money, or high potential money.
By contrast, a bank deposit is not base money, because it is a liability of a commercial bank. This normally takes a time span ranging from a few hours to a few days, depending on the country and where the check is cashed in. MT issues some e-coins, which really are digital certificates representing the property of a fixed amount of funds in the mint. This has no practical consequences, though, unless MT fails, an event which is quite unlikely. Anyway, all deposits are commercial bank liabilities, and payments by check are payments using commercial bank liabilities.