As of January 11, 2017, we’ve made changes in the way the value of
next_billing_at is handled.
Previously, if you supplied a date without a time for
next_billing_at, such as “2017-12-31”, we would set the next billing time to midnight on the specified date.
Going forward, we will instead default to noon on the specified date.
This will prevent a subscription’s billing from shifting into the next or previous day when Daylight Savings Time starts or ends in your time zone.
Of course, you can always explicitly set the time when setting the
next_billing_at, and we will use that time instead of the default.
For more information, please see Date and Time Formats in the Subscriptions API documentation.