Retaining credit for parts passed is much easier under the new exam system. Candidates automatically retain credit for parts passed for two years from the test date. This policy implies that candidates must pass all three parts within any 24 month period.
Transitioning passed parts under the old paper-and-pencil system to the new, computerized system is a little trickier. Candidates must have met the minimum retention requirements under the old rules for the exam in order to carry over credit to the new exam. See pages 8 and 9 of the EA Candidate Bulletin for further details on carryover credits.