Subtract one month from Datetime.Today

Question

I have a DateTimePicker in which I allow user to select month previous to the current year.

The problem is, that if the date is 1st January, it can\'t calc

Answer 1

Just substract a month by 'adding` -1:

var lastmonth = DateTime.Today.AddMonths(-1);

See the MSDN documentation on DateTime.AddMonths.