I have not run across options for the 5th workday of every month. However, Calendar systems will often include an option to add Holidays. Lotus Notes is a good example. You can add US, Canadian, Religious ( by Religion), and other variations, including more than one. For example, many will add US, Christian & Jewish Holidays. Other handy options includs auto blocking out weekends, with rules on whether task goes to Friday or Monday. In fairness, something like Lotus Notes, is much more involved and expensive. However, Microsoft Outlook, Yahoo & Gooogle Calendars also have this feature. I find it very handy, as work and personal schedules often overlap, but have not found on Toodledo. Could one add Holidays to Outlook, and then sync Outook with Toodledo? Have not yet tried.