From CSIA website:
The CSIA membership season runs from October 1st to September 30th every year. If you are interested in bringing your certifications back active for the current season please fill out the online application form below.
To become an active member, the reinstated membership status allows the member to reactivate his/her membership certification(s). No retest of the certification exam is required, however depending on how long you were inactive you may be required to complete a recall of your certification. To be eligible, the member pays a reinstatement fee of $97.60 in addition to the current season’s dues plus any applicable taxes.