One of the many problems with answering this question is that there are considerable difficulties in measuring intraregional inequality or income inequality for the country as a whole. There are multiple reasons for this. Firstly, the authorities in the Soviet Union after 1930's were rather averse to publishing such data. Instead, they focussed on average incomes which as Trotsky noted in The Revolution Betrayed was useful in hiding rather than revealing information. The second problem was that money did not play the same role that it did in the Western Capitalist economies or in the USSR during the New Economic Policy. Thus many of the privileges and perks that upper strata of the population, like the mangers of Successful Enterprises, enjoyed did not come in monetary terms. Thirdly, when the data was finally made public during the late period under Gorbachev, the statistics did not include the 'market income' of collective farmers which they obtained from selling their produce from private plots either to the State procurement agencies or Cooperatives. Finally, the illegal income that various intermediaries made by acting as traders between Enterprises because of the perennial shortages that managers faced that hindered or stopped production was not accounted for. They emerged during the 1960's when Khrushchev's decentralization considerably worsened the situation. According to the Marxist economist Simon Clarke and who is an expert on the modern Russian economy, these new NEPmen were the nuclei from where the new bourgeoisie emerged in 1980's.
In 1980's Goskomstat, the government agency of the Soviet Union released statistical series on personal income of Soviet citizens by individual republics for 1980, 1985, 1988 and 1990. However, even this had a limitation. The agency simply mentioned what percent of the population fell into a certain bracket (eg: 5 percent of people in USSR made less than 50 roubles a month) but not the average incomes of people within that bracket. This is important because the tables are left open-ended at the top. Having gotten that out of the way, we can get a rough picture of the intraregional inequality that existed in the USSR. The short answer is that the Baltic regions were the richest followed by Slavic regions and Southern Republics (Georgia, Armenia, Moldova) while Central Asian countries (Uzbekistan, Tajikistan) were the poorest. There were attempts to even out the differences between Republics ut it was not a priority for the State. Indeed, the use of Investment funds was based upon geographic and economic factors, the rate of return on Investment (ironic, isn't it?), transportation costs and how it affected growth rate for the USSR as a whole. Gorbachev proposed an increase in transfers from budget funds to poorer republics in 1989 but nothing much came out of it.
Per Capita household income by Republic for the Year 1988. Income is in roubles.
| Soviet Republics | Mean income | Family size |
|---|---|---|
| Tajikistan | 78 | 6.1 |
| Uzbekistan | 91 | 5.5 |
| Kyrgyzstan | 101 | 4.6 |
| Turkmenistan | 102 | 5.6 |
| Azerbaijan | 107 | 4.7 |
| Armenia | 125 | 5.5 |
| Kazaksthan | 134 | 3.8 |
| Moldova | 132 | 3.1 |
| Georgia | 141 | 3.9 |
| Ukraine | 142 | 3.0 |
| Belarus | 155 | 2.9 |
| Russia | 159 | 2.9 |
| Lithuania | 164 | 2.9 |
| Latvia | 174 | 2.7 |
| Estonia | 186 | 2.6 |
Distribution of population by per capita Household income for the Year 1990 by Republic (% each income interval) Income is in roubles.
| Republic | Under 75 | 75-100 | 100-150 | 150-200 | 200-250 | Over 250 |
|---|---|---|---|---|---|---|
| Russia | 3.2 | 8.2 | 27.2 | 26.0 | 17.3 | 18.1 |
| Ukraine | 2.7 | 8.5 | 31.2 | 28.0 | 16.2 | 13.3 |
| Belarus | 1.5 | 5.9 | 27.0 | 28.9 | 19.9 | 17.6 |
| Uzbekistan | 34.1 | 23 | 28.6 | 10.1 | 3.7 | 2.3 |
| Kazaksthan | 10.0 | 14 | 31.1 | 21.5 | 11.9 | 16.5 |
| Georgia | 6.5 | 11.2 | 28.7 | 23.1 | 14.5 | 16.0 |
| Ajerbaijan | 29.7 | 19.7 | 26.8 | 13.0 | 6.0 | 4.8 |
| Lithuania | 1.2 | 4.5 | 20.9 | 25.8 | 20.5 | 27.1 |
| Moldova | 6.1 | 12.5 | 32.9 | 24.5 | 13.0 | 11.0 |
| Latvia | 0.9 | 3.8 | 19.5 | 26.1 | 21.3 | 28.4 |
| Kyrgystan | 24.8 | 25.7 | 30.8 | 13.7 | 5.5 | 3.5 |
| Tajikitan | 45.1 | 22.7 | 21.6 | 6.8 | 2.4 | 1.4 |
| Armenia | 5.4 | 11.3 | 31.6 | 24.6 | 14.3 | 12.8 |
| Turkmenistan | 26.9 | 22.3 | 29.6 | 12.7 | 5.1 | 3.4 |
| Estonia | 0.6 | 2.7 | 15.4 | 23.6 | 21.7 | 36.0 |
So, in conclusion, there were significant gaps between each Republic. Russia was one of the richer (though not the richest) republics and there were income transfers, subsidies for the development of Industry in backward Republics which was one of the reasons why Central Asian countries did not want to leave the USSR.
Reference:
Income Distribution in the USSR in 1980's by Micheal Alexeev and Clifford Gaddy; Review of Income and Wealth, Section 1, Number 1, March 1993.
Some issues of regional inequality in the USSR under Gorbachev by Gennady I Ozornoy. Regional Studies, 25(5), 381-393.