Answer by user687474 for Difference in months between two dates

You can use the DateDiff class of the Time Period Library for .NET:

// ----------------------------------------------------------------------public void DateDiffSample(){  DateTime date1 = new DateTime( 2009, 11, 8, 7, 13, 59 );  DateTime date2 = new DateTime( 2011, 3, 20, 19, 55, 28 );  DateDiff dateDiff = new DateDiff( date1, date2 );  // differences  Console.WriteLine( "DateDiff.Months: {0}", dateDiff.Months );  // > DateDiff.Months: 16  // elapsed  Console.WriteLine( "DateDiff.ElapsedMonths: {0}", dateDiff.ElapsedMonths );  // > DateDiff.ElapsedMonths: 4  // description  Console.WriteLine( "DateDiff.GetDescription(6): {0}", dateDiff.GetDescription( 6 ) );  // > DateDiff.GetDescription(6): 1 Year 4 Months 12 Days 12 Hours 41 Mins 29 Secs} // DateDiffSample