I'll quote the relevant passage from the Wikipage, which might help you to see what I was indicating:
Ordinarily seigniorage is only an interest-free loan to the issuer. When the currency is worn out, the issuer buys it back at face value, thereby negating the revenue earned when it was put into circulation. Currently under the rules governing monetary operations of major central banks (including the central bank of the USA), seigniorage on bank notes is simply defined as the interest payments received by central banks on the total amount of currency issued. However, if the currency is collected, or is taken permanently out of circulation, the back end of the deal never occurs. Thus the issuer of the currency keeps the whole seigniorage profit, by not having to buy worn out issued currency back at face value.

Seigniorage can be seen as a form of tax levied on the holders of a currency and as such a redistribution of real resources to the issuer. The expansion of the money supply causes inflation. This means that the real wealth of people who hold cash or deposits decreases and the wealth of the issuer of the money increases. This is a redistribution of wealth from the people to the issuers of newly-created money (the central bank) very similar to a tax.

This is one reason offered in support of the creation of modern, independent, central banks whose primary objective is arguably to ensure the value of currency by controlling monetary expansion and thus limiting inflation. Independence from government is required to reach this aim - indeed, it is well known in economic literature that governments face a conflict of interest in this regard. In fact, "hard money" advocates argue that central banks have utterly failed to obtain the objective of a stable currency. Under the gold standard, for example, the price level in both England and the US remained relatively stable over literally hundreds of years, though with some protracted periods of deflation[citation needed]. Since the US Federal Reserve was formed in 1913, however, the US dollar has fallen to barely a twentieth of its former value through the consistently inflationary policies of the bank. Economists counter that deflation is hard to control once it sets in and its effects are much more damaging than modest, consistent inflation.

A seigniorage reform for the information age on a full-reserve banking base is proposed by Joseph Huber and James Robertson: Creating new money. They argue for the reappropriation by governments of the right of seigniorage now possessed by private banks. About 95% of new money currently issued takes the form of loans made by private banks to their customers. Huber and Robertson want to make this illegal. The creation of new money, both cash and non-cash should be the exclusive prerogative of the central bank. The latter should determine how much it creates in the light of the objectives chosen for the country's monetary policy and credit the new money to the government who will then put it into circulation by spending it.

However, it is important to reiterate that banks or governments relying heavily on seigniorage and fractional reserve as a source of revenue will find it counterproductive. Rational expectations of inflation will begin to take into account the bank's seigniorage strategy leading to hyperinflation which causes significant real damage to the economy. Instead of cashing seigniorage from fiat money and credit most governments opt to raise revenue primarily by other means, generally taxation.

Paul