The LEED exam process is undergoing a major revision this year. The new testing process will be harder, longer, and more expensive than the current version. However, those accredited under the old testing process will have the opportunity to "grandfather" into the new system, without taking the new tests or meeting the new experience requirements. Most people are therefore rushing to get accredited under the old system, before it gets phased out.
The new system will include two exams instead of just one: the "Green Associate" exam and the "LEED-AP+" exam. The two will roughly correspond to the FE and PE exams for engineers.
According to
GBCI, you will have the option of taking the Green Associate and LEED-AP+ exams at the same time. They will be graded separately, however, and you will need passing grades on both parts to qualify as a LEED-AP+. If you fail one part, you only have to retake that part.
Alternatively, you can take the Green Associates exam separately, and later take the LEED-AP+ exam separately. The Green Associate exam will have looser work experience requirements than the LEED-AP+ exam, just as states typically have looser requirements for the FE vs. the PE exam.
The last chance to register for the old exam is March 31. There may be some additional time to take the old exam after that date. Then the new exams will be introduced, but the exact date is unclear.