Answer by Elmer for Difference in months between two dates

This worked for what I needed it for. The day of month didn't matter in my case because it always happens to be the last day of the month.

public static int MonthDiff(DateTime d1, DateTime d2){    int retVal = 0;    if (d1.Month<d2.Month)    {        retVal = (d1.Month + 12) - d2.Month;        retVal += ((d1.Year - 1) - d2.Year)*12;    }    else    {        retVal = d1.Month - d2.Month;        retVal += (d1.Year - d2.Year)*12;    }    //// Calculate the number of years represented and multiply by 12    //// Substract the month number from the total    //// Substract the difference of the second month and 12 from the total    //retVal = (d1.Year - d2.Year) * 12;    //retVal = retVal - d1.Month;    //retVal = retVal - (12 - d2.Month);    return retVal;}