What should I use to handle time zones in scheduling?

For scheduling, the safest rule is:

Store and compute in UTC, display in the user’s local time zone, and keep the original time zone/offset when the event is meant to recur.

Practical guidance

• One-time events:
  Store the timestamp in UTC plus the user’s IANA time zone (e.g. America/New_York) if you need to show it back in the original local context.

• Recurring events:
  Store the local wall time and the time zone ID separately.
  Example: “Every day at 9:00 AM in Europe/London.”
  This handles daylight saving changes correctly.

• Never rely only on UTC for recurring schedules
  Because “9:00 AM local time” is not the same as a fixed UTC time year-round.

Use IANA time zones

Prefer time zone IDs like:

• America/Los_Angeles
• Europe/Berlin
• Asia/Tokyo

Avoid fixed offsets like UTC-5 for scheduling logic, because offsets change with daylight saving time.

Tools/libraries

Depending on your stack:

• JavaScript/TypeScript: Luxon, date-fns-tz, or the built-in Intl.DateTimeFormat
• Python: zoneinfo (built-in in 3.9+), or pytz for legacy code
• Java/Kotlin: java.time
• .NET: TimeZoneInfo
• Ruby: ActiveSupport::TimeZone

Common pitfalls

• DST gaps and overlaps
• Assuming all days have 24 hours
• Using server local time instead of a named time zone
• Storing only “local time” without a zone

If you want, I can recommend the best approach for your specific language/framework.