Slave-labor profits did not even fully cover the secret police budget.

Evidence

That the huge police organization is paid with profits from slave labor is certain; surprising is that the police budget seems not even entirely covered by it; Kravchenko, op. cit., mentions special taxes, imposed by the NKVD on convicted citizens who continue to live and work in freedom. — Hannah Arendt, The Origins of Totalitarianism, 2797

Categorization

• SHARE: A striking, specific detail worth dropping into conversation with someone interested in totalitarian economies or surveillance-state finances.
• QUESTION: Why did the NKVD need special taxes on citizens if slave labor was so lucrative? What were the actual scale of police expenditures?