There are many reasons why numerous postage stamps have received a wide variety of overprints. In some cases frugal postal administrations decided to overprint old stocks of perfectly good stamps but with completely useless denominations. Another cause for overprints has been rampant inflation rendering the stated value of no use. Major political developments have also been the reason for overprinted stamp issues.
One of the most common reasons for the surcharging of stamps with new denominations is the change of postage rates. Frequently such decisions are made at short notice, giving the postal authorities very little time to prepare and print new stamps with denominations reflecting the new rate schedule. In most cases the rates are increased but this is not always the case. Surcharging existing stamp stocks with new and more useful denominations can be a most effective and rapid way of producing the required stamps at a modest cost. The new value is simply printed on the stamp – frequently with a black bar covering the original value.
This happened in Sweden in June 1918. Parliament wanted to increase the postage rates in order).
