The first official flag of the Soviet Union was adopted in July of 1923. It was of a 4 to 1 ratio in proportion and consisted of a red flag with the state coat of arms in the center. This flag was the official flag for four months, and was replaced as the official flag by the more familiar "hammer and sickle" design on November 13, 1923.
A modification to the flag was adopted on August 15, 1980 making it solid red on the reverse side with no hammer, sickle or other decoration. In addition the color was brightened at that time.
With disintegration of USSR on December 3, 1991, the flag ceased to be a national flag.
On April 15, 1996 Boris Yeltsin signed a presidential decree giving the Soviet flag (called the Victory Flag, after the banner that was raised above Reichstag on May 1, 1945) the status similar to that of the national flag.
This flag was the official flag for four months, and was replaced as the official flag by the more familiar "hammer and sickle" design during the third session of the CIK of the USSR on 12 November 1923.
The newly adopted official flag of the Soviet Union consisted of a plain red flag, with a hammer crossed with a sickle and a red star in the upper hoist.
With disintegration of USSR on December 3, 1991, the flag ceased to be a national flag.