But why? If the relation between money growth and inflation is so clear, why don't these countries simply print less money? If only it were so easy! The real problem most of these countries had was a large fiscal deficit. Let's think how that influences monetary policy. If a government is running a deficit, then it must issue iou's of some sort to pay for it. Roughly, speaking, it may issue money (dollar bills or their local equivalent) or interest-bearing debt (treasury bills and notes) denoted with the variable B. Mathematically we can express this as
Pt (Gt - Tt) = dMt + dBt,
or, in real terms:
Gt - Tt = dMt / Pt + dBt / Pt
where the two terms on the right are issues of new money (dM) and new interest-bearing debt (dB), respectively. This is an example of a government budget constraint: it tells us that what the government doesn't pay for with tax revenues, it must finance by issuing debt of some sort.
So why do these countries increase the money supply? The problem, typically, is that a political impasse makes it nearly impossible to reduce the budget deficit. Given the government's budget constraint, it must then issue debt. Now for US debt there is apparently no shortage of ready buyers, but the same can't be said for Argentina or Russia. If they can't issue debt and they can't reduce the deficit, the only alternative left is to print money: in short, when they can't pay their bills any other way, they pay them with money, which is easy enough to print. The effect of this, of course, is that these countries experience extremely high rates of inflation.
Note that whenever a central bank prints "fresh money" it can obtain goods and services in exchange for these new pieces of paper. The amount of goods and services that the government obtains by printing money in a given period is called "seignorage". In real terms, this quantity of goods and service is given by the following expression:
Seignoraget = dMt / Pt = New bills printed during the period / Price level during the period.
The monetary aggregate that the central banks control directly is the "monetary base", consisting of currency in the hands of the public and reserves of the commercial banks deposited in the central bank. Thus, when we refer to a central bank as "printing more money", we mean increasing the monetary base.
Note that since the government, by printing money, acquires real goods and services, seignorage is is effectively a tax imposed by the government on private agents. Such a seignorage tax is also called the inflation tax. The reason is the following. From the definition of seignorage:
Seignoraget = dMt / Pt = (dMt / Mt ) (Mt/Pt)
Since the rate of growth of money (dM/M=m) is equal to inflation (p) (assuming, for simplicity, that the rate of growth of output 'y' is zero), we get:
Seignoraget = pt (Mt/Pt)
In other terms the inflation tax is equal to the inflation rate times the real money balances held by private agents. This makes sense: the inflation tax must be equal the tax rate on the asset that is taxed times the tax base. In the case of the inflation tax, the tax base are the real money balances while the tax rate at which they are taxed is the inflation rate. In other terms, if I hold for one period an amount of real balances equal to Mt/Pt, the real value of such balances (their purchasing power in terms of goods) will be reduced by an amount equal to pt (Mt /Pt) after one period. The reduction in the real value of my monetary balances caused by inflation is exactly the inflation tax, the amount of real resources that the government extracts from me by printing new money and generating inflation.
http://pages.stern.nyu.edu/~nroubini/NOTES/CHAP6.HTM