GET /v1/periods lists them.
OPEN, CLOSING or CLOSED. Closing is done in the console by an approver who has confirmed their identity, after the close checklist passes. A key cannot close a period.
What closing means for you
An entry whose business date falls in a closed month getsPERIOD_CLOSED. Post it dated in an open period instead.
A partner’s credit cannot be refused, because the money has already arrived. A late inbound credit is booked on the first open day, with latePosting: true.
Business dates
An entry belongs to a period by itsbusinessDate, not by the UTC date. See Money and data formats.