Keep that in mind if you make formatting changes to the planner.
If you want a monthly calendar that will store yearly events and holidays, try Excel Calendar Pro (not free). Then you can enter holidays, events, and birthdays directly into the monthly planner. Just right-click on the planner worksheet tab, select 'move or copy.', check the 'copy.' box, click on OK, and then rename the new tab to Jan, Feb, etc. Instead, it lets you duplicate the planner worksheet so that you have a separate month on different tabs. Unlike our daily and weekly planners, this planner does not automatically add holidays and birthdays.
Change fonts, add some color, add cute little images on specific days. If you insert rows or insert columns into the calendar-portion of the planner, the formulas used for the dates will be messed up, but other than that, it is pretty simple to customize. Our spreadsheet gives you a great deal of flexibility to customize your own personal monthly planner.