I think Google Calendar is brilliant however
one type of repeating event it does not support is the last specific 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-wed-of-month.ics and put this inside it:
SUMMARY:Last Wednesday of Month
DESCRIPTION:Last Wednesday of the month
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.
If you need to do a different day to Wednesday, change
BYDAY=WE to match the day you require (one of SU,MO,TU,WE,TH,FR,SA)