As the title asks, because I'm getting various responses from around the way, things such as "You need 5-6 0's in front of the number" or "Anything under A00010000A" or "If it's under 4000 it's from the first printed block, and therefore low" I ask because I've got two things, a 2017A $20 with PE00006307B And just today at work counting the $500 in 1's from Loomis for our store change, I buy this out the lot: Is it considered a Low Serial? Is the $20 even considered as well? Either way finding notes with 4 forward 0's for me is very rare so I'm keeping it, but I'd just like to know...
Simple answer is a low serial number is one that a collector is willing to buy at a premium. Historically, this has been 5 leading zeros. Sometimes, you can get lucky on ebay and somebody may bid a few bucks on 4 leading zeros, but that's more of an exception. Nothing wrong with saving the dollar you posted. I would. However, I would be hesitant to save higher denominations with 4 zeros. Not worth tying up the funds IMO
The majority of collectors of these types consider a serial number to be low if there are 5 leading zeros. The lower, the better. Your bill is a little bit high but given the condition I’d keep it.
I would go with Steve's answer. Other serial numbers you mentioned (like 00001000, 00002000, or 00010000, 00020000) are thousand & ten thousand # notes (respectively) & would definitely demand a premium (but they're not technically considered low #).
I agree with @SteveInTampa with <999. Some serious note collectors won't touch it unless it's below 6 leading zeros, <99.