I get what you're trying to say, but it's kinda self-contradictory. If the people have to pay the government to be together and have children, wouldn't that be seen as population control instead of population increasement?
Secondly, government does not force people to be married in order to have children. It's a mental control, not physical. People BELIEVE they first have to marry (or in other words, consent to the government and pay them for the invisible priviledge) in order to have a family and children.