It varies by era. As far as I know, microbusinesses were common prior the collectivization of the 1930s, and businesses as we know them were practically encouraged after the mid‐1980s, but otherwise they were disallowed. Instead, the state fulfilled the rôle of producing and distributing goods, specifically through enterprises. Here is one (counterrevisionist) communist’s assessment:

‘The product of the state-owned industrial enterprise was allocated by the state – i.e., the state told the enterprise how much to produce and who to deliver the product to. The industrial enterprise was not meant to freely sell any surplus over this planned amount, though they would get a bonus for over-fulfilling their plan target. In the case of the collective farm, the collective had to deliver a fixed quota to the state. Everything they produced above this quota was essentially a profit. The collectives could sell this surplus product and the proceeds would be distributed among the collective’s workers.’

(Source.)

An ultraleft view is the kolkhos was basically a business and, for example, ‘that it is market laws and not the most fundamental needs of workers which determine qualitatively and quantitatively kolkhosian production.’ How accurate that is, though, I can’t say for sure, but counterpoints are welcome. For a closer examination of how state enterprises functioned in the U.S.S.R., you can check out Is the Red Flag Flying? for details.

I realise that this is a questionable response, but I hope that it helps.