What you're advocating is akin to a sin tax, similar to taxes on cigarettes (especially) and alcohol. In order to encourage our view of right behavior (says government), we will discourage what we deem as wrong behavior by taxing said behavior. Frankly, I'm not a big fan of using taxes to affect behavior, ie. legalize drugs and tax them highly.

For one, it brings up the dilemma of trying to capitalize on higher tax revenues (increased spending being inevitable) while theoretically trying to reduce the behavior, which would produce lower tax revenues if successful.

Secondly, while I can see the value in creating incentives in the tax code for behavior we regard as beneficial (for example, home ownership), I don't like the idea of punishing legal activity.

Ok, so abortion, cigarettes, booze and fast food may be bad things in the view of many people, but they are legal, so what gives anyone the standing to effectively punish this behavior through taxation. How far do we go, and who decides? Do we increase taxes on fast food, SUV's, the lottery, guns? If the behavior is so detrimental that it needs to be punished, than make it illegal. Otherwise, you are simply looking for a way to appropriate more money from the taxpayer and not have to feel guilty about it (they deserved it).

Now, to your specific proposal. I have questions regarding a state versus federal tax and if that tax (actual dollar amount) should differ between states based on standard of living, but I won't really address those issues.

My first problem really does depend on the state versus federal issue, though. Different states already have different restrictions on abortion; would this replace those restrictions or supplement them? Your proposal allows for abortion at term. I'm not sure how many places that's currently allowed by law, but it's not many and probably fewer still in actual practice. I believe if your proposal supercedes current abortion law, it would increase late term abortions by giving it more availability. Most doctors may still opt not to perform a late term abortion for moral reasons, but some who currently don't might start if they see your proposal as basically state sanction (if the price is right, which sounds repulsive to me as I type it).

Furthermore, seventeen states publically fund all or most "medically necessary" abortions. I'm not sure what constitutes medically necessary, but it is not just life endangerment. Would they not just fund the taxes as well, meaning all taxpayers would end up paying the tax?

Subsidizing adoption sounds good in principle, but it would probably just cause adoption costs to rise. Hey, government is going to cover part of it, so we can charge more (say adoption agencies). It already happens with Medicare. Why would this be any different? And you have already touched on the bureaucracy that would exist for the tax itself.

Honestly, I believe you're overthinking things. There are only three highly viable solutions as I see it. Overturn Roe and let the states regulate abortion as they choose (like we do the death penalty), make abortion illegal, or make abortion a constitutional right.

I believe the latter two are the only possible federal interests, and I believe both options should require a Constitutional amendment. Barring an amendment either way, Roe should be overturned and the issue sent back to the states.

I tend to think of sin taxes as a bad idea, because they tend to punish addictive behaviors. (Though they are avoidable, which is a good characteristic for any tax.)

But I don't tend to think of this as a sin tax. The idea of a sin tax is to punish behavior that society finds "bad", but which making illegal would not work (see prohibitions on alcohol or the current "war on drugs"). The idea here is not to punish abortion, but to set up incentives for both parents and prospective adopters to make adoption a more rational choice than abortion when the abortion is for "lifestyle" reasons (hence the times it wouldn't apply, like when "medically necessary"). In other words, this would supplement current abortion law, not replace it.

I'm not terribly concerned about the cost rising, because abortion is not a cartel (as health care is), but it is highly regulated (in fact, most of the costs come from state fees of various kinds). The tax would offset the various state fees, rather than being sent directly to taxpayers or to the adoption middlemen.

I agree that Roe should be overturned and abortion should be a political issue (and suspect we'd come to a cultural compromise fairly quickly, which we cannot do while the issue is enshrined as an emanation or penumbra of the Constitution). That said, it's just shifting the ball downfield: once the states have the issue, those that choose not to make abortion blanket illegal would have to decide how to regulate it, and this proposal would still be valid.

I still look at this as punishing a behavior that isn't illegal. Telling a woman she'll be taxed if she decides to have an abortion (outside 12 weeks in your example) is not an incentive to carry the baby to term; it's a disincentive to abort. Maybe that's a distinction without a difference in effect, but if the behavior is legal, it should not be punished (taxation sounds like a punishment to me).

I agree we should find incentives to increase adoption, and I would love to have fewer and fewer abortions. Lowering the cost of adoption would definately be beneficial on that end, but I think there may be a better way to approach the problem at the other end.

Just don't ask me what that way is, because I don't know off-hand.