It has been clear over the last few years that incentives and positive reinforcement are not helping stem reduced fertility levels in countries globally. At best they are making the decline less bad, but not stopping it. For counties with an iron grip over their citizens, unimaginable responses might occur. Keep in mind China’s historical, rigid one-child policy (unless you were rich).
Now, Russia is starting to get aggressive. Lawmakers have proposed a ban on “propaganda of conscious refusal to bear children,” https://www.nbcnews.com/news/world/russia-proposes-ban-child-free-lifestyle-rcna172616
When the parameters are ill-defined, and the punishments severe, expect the Russian populace to be very careful about any mention of choosing to not have children, anything gay, ideas on global over-population, and so on.
It won’t work, of course. Baby-making is such a serious part of life, people will still make their own conclusions and decisions.
Then what will follow will be punishment (not taxation) for those who go child-less. China will do the same and all other communist countries. Capitalist countries will rely on immigration, for now.