I know that the first letter is different, but does the second letter range from A to Z or does it stop at a particular letter and move on to BA, BB, etc? I searched up a random code beginning with AZ onto a banknote serial checker, but it didn't come up with anything. Any help?
-Great question @amaturerollcoins & one I have been working on for the last 6 years or more.
The general rule of thumb is AA22, AB22, AC22, etc using up a preset list of letters until transitioning to BA22, BB22, BC22, etc. The prefix includes the last 2 numbers of the year the note was printed so the examples I have provided are examples if a new series were started this year (2022). However, RBA has been issuing notes from 2020 so notes go from AA20 to EJ20 for the $5 (etc).
Generally the prefixes carry on from years before & the year notes printed change. The signatures (Governors/Secretary to Treasurer) may be changed (newly appointed) while the prefix letters change. That is why 1 prefix (per denomination) may change
& be short (& those are the ones collectors go for).
For example, if you SELECT THE YEAR: 2002 on the RBA site, you will see that the McFarlane-Henry prefixes start at BA02 & end at EA02. If you go on the Coins And Australia site, you'll see that the BA02 & EA02 have extra premiums:
(CCF won't allow me to post the Coins and Australia site but you can find it on google)
I have used the BNM (Bank Note Museum) also for a guide:http://www.banknote.ws/COLLECTION/c...%20AUSTRALIA
Coins And Australia's site also has a guide for pre-decimal too (just google it).