Make date and timezone settings: convert to Japan time and compare deadlines

Define what the deadline actually means

A date such as November 2 is not the same as an instant such as November 2 at 10:00. Set the business closing time before comparing a date-only deadline. This example uses 17:00 in Asia/Tokyo and separates the stored instant from its display. Treating a date-only value as UTC midnight without a rule can shift which day receives a reminder.

Identify the source timezone

A timestamp ending in Z represents UTC. A local value such as 2026-11-02 10:00 needs a source timezone before it can identify an instant. Inspect the Make organization timezone and any timezone explicitly supplied to functions. The timezone shown on the operator's computer is not necessarily the timezone used by the scenario or its source data.

Parse text into a date value

Use the source format and timezone when converting local text. An example expression is parseDate(input; "YYYY-MM-DD HH:mm"; "Asia/Tokyo"). Clarify ambiguous month/day formats instead of guessing. If the upstream value is already a date, use it directly where appropriate; repeatedly formatting and parsing it introduces opportunities to lose offsets, precision or date information.

Use formatDate for presentation

A display expression is formatDate(date; "YYYY-MM-DD HH:mm"; "Asia/Tokyo"). It creates text representing the instant in that zone; it does not move the instant forward nine hours. Adding nine hours is a different operation. Applying both a timezone conversion and an extra offset can double-correct the value, producing a convincing but incorrect appointment or reminder time.

Compare dates with explicit interval boundaries

Define a window such as after the previous checkpoint and up to the current checkpoint, specifying which endpoint is inclusive. Compare date values rather than formatted labels or day-of-month alone. Combine the deadline test with notification state. If a scheduled check runs late, use a recorded checkpoint to investigate whether eligible items can still be recovered instead of missing them permanently.

Test midnight, month ends and daylight-saving changes

Compare 23:59 with the next day's midnight, the last day of a month with the next month, and offset-bearing versus local representations of the same instant. Overseas local times may be nonexistent or repeated during daylight-saving transitions. Use named timezones and agree how the sender disambiguates local timestamps, preferably with an explicit offset where needed, rather than assuming a fixed difference all year.

Retain interpretation and reminder history

Keep the original input, its interpreted timezone and the confirmed deadline distinct enough to diagnose a discrepancy. Track reminders against the item and the deadline version so a rescheduled deadline can follow a defined notification rule. Date conversion alone does not implement public holidays or business days; those require a separate business calendar. These are proposed boundary checks rather than measured scenario results.

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