using System;

using System.Globalization;

public class Program

{

    public static void Main()

    {    

        var now = DateTime.UtcNow;

​

        var targetDue = "2021-03-02T09:00:00.0000000Z";

​

        Console.WriteLine("Date Time Parse: " + DateTime.Parse(targetDue).ToString());

        var diff = DateTime.Parse(targetDue).Subtract(now);

        Console.WriteLine("Diff: " + diff.ToString());

​

        // Returns a 'TimeSpan' representing the difference

        var difference = DateTime.Parse(targetDue).Subtract(now);

        Console.WriteLine("Difference: " + difference);

        var quarter = now.Add(System.TimeSpan.FromTicks(diff.Ticks));

        Console.WriteLine("Quarter: " + quarter.ToString());

    }

}