When Is Paper Money Considered Old

interesting question.... I have no clue but am now interested myself. Great question.

Pick up the "Guide to Small-Size Paper Money" from 1928-date. In there it lists all production numbers of notes. Sometimes with frn's it's not the date that makes them collectible but the amount that were printed from that frb. Ie- The 1928 red seal $2 would definately be considered an "old" note. Valued from $8-$40, doubt you would find it in circulation now. What you can find in circulation now is the 2003a $2 star note(only * printed in 2003a for $2 bills)(I think only 320,000 printed) and that sells easily for $40-$95 on ebay now.

It's just like collecting anything else, rare items are more valuable than old. I'd rather have a Mantle rookie than an older common card.

the thing about paper money they don't change dates unless there is a design or signature change so you may get a 2006 that was printed in 2010. You can't just go by the date on the note. This is at least how it was explained to me a few years ago

It still comes down to personal preference, in my opinion. I usually take any notes I find from 1995 and earlier out of circulation. Through it is true age is not a major deciding factor in value as is rarity of the bill, I still feel it plays somewhat of a role. And so, depending on how old YOU are and how long you plan to collect for, taking a bill that's 15 years old out of circulation could be a good idea. If you plan to collect/live for 50 more years then the bill will be 65 years old. Who knows how much paper money will change in appearance or if it will exist at all - or if we will exist at all. And trying to determine how the value of paper money will change in the future is pretty much a lost cause at this point.