§ 520. Base period. A claimant's "base period" is one of the
following:

1. For the purpose of subdivision one of section five hundred
twenty-seven of this article, the term base period shall mean the first
four of the last five completed calendar quarters ending with the week
immediately preceding the filing of a valid original claim.

2. For the purpose of paragraph (a) of subdivision two of section
five hundred twenty-seven of this article, the term base period shall
mean the last four completed calendar quarters ending with the week
immediately preceding the filing of a valid original claim.