According to documentation, the maintenance.create method should uphold these parameters as default when creating a new maintenance:

active_since timestamp Time when the maintenance becomes active. Default: current time.

active_till timestamp Time when the maintenance stops being active.
Default: the next day.

See https://www.zabbix.com/documentation/3.0/manual/api/reference/maintenance/object

However, when trying to create a new maintenance via the API without specifying active_since and active_till, the API fails with one of the following errors:

"Active since" must be between 1970.01.01 and 2038.01.18.
"Active till" must be between 1970.01.01 and 2038.01.18.