Schengen Zone

"My question is: because I will have spent more than 90 days outside of the Schengen Zone, does my 90/180 restart when I go back in May?" No. "when I go back to Europe in May, will this be seen as a continuation of my original trip because it is within 180 days of when I first entered Germany in December?" Yes. "If so, do I wait to go back into the Schengen Zone once that original 180 day period has expired, (around June 20), and then my 90/180 count will restart?" Yes again. "Or will I need to wait another 90 days following the expiration of that original 180 days for the count to restart?" No.

Your "more extended period" that starts in May: how much more extended? Will there be any day in the second trip that if you count back 180 days from that day you will have been in the Schengen area for partial or whole days numbering 90 or more? No? No problem. Yes? Problem. There is a very good website which does day calculations well which I use: http://www.convertunits.com/dates/ It appears that your first trip will use 17 days of your allowance, leaving 73 within that first 180. If the second trip is 73 or fewer days it won't matter at all when it is.

As was mentioned above, when you leave in January, you will have used 17 of the 90 days, leaving you with 73 more to use. The first 180 days is up about June 18. If you re-enter in May, you will not use the 73 days by June 18. At that time, you will lose 1 day from the previous (rolling) 180 days every day you are in until June 18, when the total number of days will just be the time you've been in since May. So, essentially, you can come back in May and spend another 90 days. In other words, on June 19, 2014, only days used for the last 180 days, since December 22, are counted, on June 20 it's since December 23, and so on. When you get to July 4 (180 days since Jan 6), only days since you entered in May would count. At least that's the way I interpret the 90 out of any 180 day period rule.