The research appears to challenge Russian claims over investment flowing into Latvia and the Baltics during the soviet period.
While many documents that would shed light on the issue are stored secretly in Russia, Krūmiņš found USSR Gosbank (central bank) documents in Latvia's State Archive and Bank of Latvia archives - and, later on, similar documents in Estonia and Lithuania - that paint a detailed picture of budget income and expenses in the Baltics.
"The documents identified in Baltic States' archives permit making estimates about all the income and expenses in the Baltics during the period of soviet occupation, including the expenses of the USSR occupation regime for the goal of funding military and repressive institutions," writes Krūmiņš.
Krūmiņš has found that from 1946 to 1990 a total of 24.684 billion rubles were spent from the USSR budget in Latvia, while 40.645 billion went to USSR coffers. The estimates take the 1961 currency reform into account.
That means that the Soviet Union received 15.961 billion more than it invested into Latvia.
"The estimates bust the myth - hatched during the USSR period and propagated even now - about USSR investment in Latvia and the Baltics as a whole and proves the opposite - that Latvia and the Baltics as a whole were donors to the USSR economy," writes Krūmiņš.
Krūmiņš found a similar tendency of revenues to the USSR budget exceeding expenses while researching USSR Gosbank documents in Estonia and Lithuania.
The full research paper is available here in English and is the first instalment of an upcoming five-part series about the USSR's financial policies in Latvia.
Previously a committee set up to calculate the losses to Latvia caused by the soviet occupation claimed that the country's economy suffered losses of €185 billion during the period.