Handle dates, time zones and clock changes in code

Use this guide if your code stores appointments, timestamps, reminders or reports, especially before the clocks go back on the last Sunday in October. You need access to the code that creates, saves and displays times, and ideally a test setup where you can try specific dates.

Step by step

1. Find every place times enter and leave

   List where your system creates a time (user input, now(), imported files, APIs), where it stores it (database columns, files) and where it shows it (screens, emails, exports). For each, note whether a time zone is recorded or merely assumed. Times with no zone attached, often called naive times, are where most clock-change bugs hide.