Type 1.
In June 1927, a black typographic overprint "Postage / stamp / kopeks. 8 kopeks." was applied to the 1925 USSR postage due stamps. They were used as regular definitive stamps. The overprint exists in two types. Twenty-two different inverted overprints are known.
A postage due stamp is a postage stamp used to collect a postal fee from the recipient: when a postal item is sent with insufficient postage or with unpaid postal charges; for postal items whose delivery must be paid specifically by the addressee. Postage due stamps were distinguished by the fact that they were not sold to the public, but were affixed by postal employees to correspondence paid by the sender below the current rate, while the amount of the surcharge was collected from the addressee upon delivery of the correspondence. In the USSR, postage due stamps were issued up to 1925.
From May to October 1925, two series of postage due stamps of different denominations were issued and used until February 1, 1926. Later, instead of postage due stamps, postage due handstamps with the inscription "To be paid" or "Surcharge" began to be used.