Why deleted dates of a recurring event still show up

The short answer

A calendar file stores a repeating event as one entry with a rule, such as every Thursday at 7, plus a list of dates to skip. When you delete one date, people's calendars keep showing it until their app downloads the file again. For Google Calendar that comes every 12 to 24 hours, by the estimate of AddEvent, a company that hosts subscription calendars. Anyone who imported the file or used an “Add to calendar” button has a copy that never hears about the change. If the date is still in your published file, delete it again in the calendar you publish from, as a single occurrence.

How does a calendar file store a repeating event?

The calendar file standard, RFC 5545, keeps a series as one event with a start time and a repeat rule. Dates taken out of the series go in an exception list. Each app works out the dates for itself, taking every start the rule produces and dropping the ones the exception list names.

Line in the file	What it says
`DTSTART;TZID=America/Chicago:20261001T190000`	The first one is Thursday, October 1, 2026 at 7 PM Central.
`RRULE:FREQ=WEEKLY;BYDAY=TH`	It repeats every Thursday.
`EXDATE;TZID=America/Chicago:20261126T190000`	Skip Thanksgiving, November 26.
`RECURRENCE-ID;TZID=America/Chicago:20261119T190000`	Found on a second entry with the same UID: this replaces the November 19 date, for example after it moved to Wednesday.

That last line is how the standard handles one changed date. The RECURRENCE-ID names the original start, so the app knows which date the edited copy stands in for.

Why does a deleted date still show?

Their app hasn't fetched the file since. AddEvent, which hosts subscription calendars, puts Google Calendar's checks at every 12 to 24 hours. Microsoft's estimate for Outlook.com is every 3 hours, with some changes taking more than 24. Our guide on why a subscribed calendar isn't updating lists each app's timing.
They have a copy. An imported file or an “Add to calendar” button leaves people with events of their own, which Microsoft calls a snapshot that won't update. They'll have to delete the date themselves. The guide to buttons and subscriptions explains the difference.
The exception names a different time. The standard drops a date only when an exception names that exact start. Say a series moved from 7 PM to 8 PM after a date was taken out. An exception left at 7 PM matches nothing, and the 8 PM date stays.
The date came out of a different calendar. Deleting it from your personal calendar leaves the published one as it was.

How do you check the published file?

Open your calendar's link in a browser and save the file, swapping webcal:// at the start for https:// if it has one. Open the file in a text editor and find the series by its title on the SUMMARY line. Look below it for an EXDATE line with the deleted date. An EXDATE line for that date means the file is right and people's apps have yet to catch up. If you can't find one, go back to the calendar you publish from and delete the date again as a single occurrence.

How TheyCal handles repeating events

We make TheyCal, and it sends every date as an event of its own, with no repeat rule for an app to work out. When a business cancels one date, that event comes off people's connected Google and Outlook calendars and drops out of their calendar links at the app's next refresh.

Businesses that keep their schedule in another calendar can have TheyCal read its link. We expand its daily, weekly, monthly and yearly repeat rules over the next 12 months, skipping the exception dates. Where one date in a series was edited, the edited version takes its place. An upcoming date that disappears from that calendar gets cancelled when we next read it, which we do daily.

Common questions

Do subscribers need to do anything?

Nothing, if they subscribed to the link: the change reaches them when their app next downloads it. Anyone who imported the file or added the event with a button has to delete the date by hand.

How long until the date disappears?

It depends on the app. AddEvent puts Google Calendar's checks at every 12 to 24 hours, and Microsoft's estimate for Outlook.com is every 3 hours or so, with some changes taking more than a day.