Use year determines when your points are added to your account each year and it determines your banking deadlines. Use year has nothing to do with when you can call to make a reservation.
Use year only matters if you have to cancel a trip that occurs late in your use year. That's because after your banking deadlines pass, you must use your current year points before the end of the use year or you will lose them.
For example, let's say you planned a trip for February 12 - 19, 2005 that requires 150 points. Let's also say that you have a total of 300 points. That February trip falls within your 2004 use year. (With an April use year, your 2004 points are good for stays between 4/1/2004and 3/31/2005).
Let's say you have to cancel that trip in December, 2004. Since that is at least 31 days in advance of arrival, you get the 150 points back into your account. The points expire on 3/31/2004 unless you can bank them. With an April use year, your 50% banking deadline is the end of December. So if you couldn't reschedule the trip before the end of your use year (3/31/2005), you could bank the points.
Assuming you call before 12/31/2004 with your banking request ,and assuming that you haven't previously banked any of your 2004 points, you could bank all 150 into your 2005 use year. That means you can use them between 4/1/2005 and 3/31/2006. Great!
Now let's suppose you didn't cancel that trip until January 2, 2005. Still more than 30 days in advance of arrival, but now you would only be able to bank 25% of your total allotment or 75 points if you called to do so before the end of January. If you couldn't use the remaining 75 points by 3/31/2005, they would expire and you would lose them.
To sum it all up, use year ONLY matters if you have to cancel a trip that is planned for the last few months of your use year.
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