One issue is that the childless will wind up requiring more state care as they age (since they won't have family to care for them). A possible solution would be to slightly increase taxes on childless to make up for that difference.
Look at it this way, properly incentivizing children would mean that the average couple with two kids would pay zero net taxes over their life. With zero rates a non taxpayer who reproduces at replacement has the same equivalent fiscal value as a childless full taxpayer.
Punishing people for not having kids is obviously ridiculous.
It doesn’t seem like “promising my kids will pick up the tab at replacement rate” is enough to be stable.
That doesn't seem like a terribly effective "solution" unless the goal is to maintain the status quo, especially given the vicious cycle it introduces.
What was never set up as a savings account?
My comment was pointing out the absurdity of taxing a specific group of people more because in their old age they will become a greater burden on the state than another group. Consequently forcing them into becoming dependent on the state by reducing their ability to save and invest for themselves. It's a vicious cycle and the original commenter doesn't seem to recognize the absurdity of that position. In the OP's proposal, I'd have higher tax rates because I've not yet had children. But once I do have children, what, do I get it all back? Or am I just forced to suck up the unnecessarily reduced income for the past 20 years? What if my children (god forbid) don't survive to adulthood themselves. Will I start getting taxed more again due to this tragedy? Of course, this already happens now as you lose a dependent for tax purposes.
The position is absurdist unless the objective is to further reinforce dependence on the state.
I'll point out that the OP suggests increasing taxes on the childless over what they are already taxed now. Which suggests a greater swing than just the loss of a dependent on your taxes in the case of the death of your children. Adding insult to injury, as it were, for my last question.
Not getting dependent/child tax credits already does this.
We might also want to encourage some level of additional population growth. This is best done by providing support for parents.
It is better to incentivize behavior by providing services that help people do the things we want. Attempting to punish people will just cause anger, and even if the punishment is doled out for good reason (which, I'd say it isn't a good reason in this case), some level of misstargeting is inevitable.