I need to set up billing cycles and process payments. So for example I will process a payment immediately and then set the next one up to process exactly one month from then
The aptly-named "AddMonths" method comes immediately to mind.
DateTime has a set of Add methods such as:
etc.
More information at DateTime methods.
Try this:
DateTime myDateTime = DateTime.Now.AddMonths(1);
If you ever need to work with Quarter or WeekOfYear, Microsoft.VisualBasic.DateAndTime.
http://msdn.microsoft.com/en-us/library/microsoft.visualbasic.dateandtime_members.aspx
Otherwise, System.DateTime does everything you would typically need.