Create Repeating Google Calendar Event for Last Day of Month

I think Google Calendar is brilliant however
one type of repeating event it does not support is the last day of the
month. There is the option to import a custom ICS file though and within the
specification of that file format you can do it.

Create a new file, ie last-day-of-month.ics and put this inside it:

BEGIN:VCALENDAR
VERSION:2.0
BEGIN:VEVENT
RRULE:FREQ=MONTHLY;INTERVAL=1;BYSETPOS=-1;BYDAY=SU,MO,TU,WE,TH,FR,SA
SUMMARY:Last day of the month
DTSTART;VALUE=DATE:20220421
SEQUENCE:0
DESCRIPTION:Last day of the month
END:VEVENT
END:VCALENDAR

Save that and then import into Google Calendar
and it’ll create you a new event that repeats on the last working day of the
month. If you need help importing into Google calendar then see this page in Google’s help docs.