If you are only concerned with the data display format on Reports you might print using this number then you should just have to set the Format property of the field to something like...
000000-00-0000
should work.
Just as an aside, generally speaking if you do not intend to do any math with numbers that you store in your DB, then it is best to store then as text. You have more flexability with strings. So I would store your Id numbers in Text fields if you can.
Good Luck
Chris
