It's important to keep use years straight. In the OP we're talking about two different use years.
For a SEPTEMBER use year, the January 2004 vacation is part of their 2003 use year. The October 2004 vacation is part of their 2004 use year.
In chart form it looks like this:
<b>Year.....Vacation Dates</b>
2002.....Sep 1, 2002 thru Aug 31, 2003
2003.....Sep 1, 2003 thru Aug 31, 2004
2004.....Sep 1, 2004 thru Aug 31, 2005
For a September use year, you can bank 100% of your points by the following Feb 28th.
Now I'll rephrase the next two. You can bank <b>or already have in the bank</b> 50% of your annual points by the following May 31st.
You can bank <b>or already have in the bank</b> 25% of your annual points by the following June 30th.
So, if you have a 250 point contract, let's say by Feb 28th you bank 200 points. When May 31st comes you may NOT bank any additional because the max for May 31st is 50% or 125 points and you already have 200 banked.
2nd example, suppose you bank 50 points prior to Feb 28th. Now when May 31st comes around you have only 50 points banked, but you're allowed to have 50%, or 125 points banked, so you may bank an additional 75 points to bring your total to 125 points (50%)
As to YearLightBuzz's question, if you had 250 points, spent 214 points leaving 36 points, and have no points banked at all, then you have until June 30th (for September use year points) to bank them because you're allowed 25% at that time which would be 62 points (MS rounds DOWN). So you could bank up to 62 points which covers all the 36 points in question.
Hope this answers your question without getting too long.
Remember all examples above are for a SEPTEMBER use year. The banking dates for all other use years are different.
Bill