Originally Posted by NoSoup

Yep -

Unless, of course, you are rolling over pre-tax dollars from another retirement vehicle, such as a 401(k) or the like, then it is done up front.

As for this next part, it's been a couple of years, so Gar1976 probably should verify, but....

I think you are able to deduct either all or part of your contribution, based on your income, filing status, ect. However, if you contribute more than you can deduct, you can leave that money in there as a "nondeductable contribution." If you do that, you aren't taxed on that money when you later withdraw it, as taxes have already been paid.