Get the First Day of Next Month in C#

public static DateTime GetFirstDayOfNextMonth(DateTime startDate)

if (startDate.Month == 12) // its end of year , we need to add another year to new date:

startDate = new DateTime((startDate.Year + 1), 1, 1);

else

startDate = new DateTime(startDate.Year, (startDate.Month + 1), 1);

return startDate;