Billing operations
Billing Period Cutoffs: Time Zones Are Part of the Contract
By the Orvlin team · · 2 min read
Billing period timezone cutoffs: what to decide
A customer sees activity on October 1 while the invoice assigns it to September. Both views might be mathematically correct in different time zones, but the unexplained mismatch invites a dispute. Period definitions should travel with the data.
A half-open interval includes the start and excludes the end, avoiding overlap between adjacent periods. Subscription anniversaries can differ from calendar months. If local-time billing is used, daylight-saving transitions require careful duration and boundary handling.
An illustrative case
A period from October 1 at 00:00 UTC to November 1 at 00:00 UTC includes an event at October 31 at 23:59 UTC but not one exactly at November 1 at 00:00 UTC. The next period includes that boundary event.
The important caveat
Never strip timezone information and hope a later system guesses correctly. A timestamp without an offset can be ambiguous, especially around daylight-saving changes and multi-region ingestion.
Review these decisions
- Document timezone and inclusive boundaries.
- Keep occurrence and receipt timestamps separate.
- Test events exactly on the boundary.
- Show the period definition in exports and disputes.
Frequently asked questions
- Should we always bill by calendar month?
- No. Anniversary periods and other contract schedules can be valid. Choose a schedule the buyer understands and implement it consistently.