using System;

using System.Globalization;

using System.Threading;

using Newtonsoft.Json;

public class Program

{

    public static void Main()

    {

        Calendar cal = (Calendar)CultureInfo.CurrentCulture.Calendar.Clone();

                cal.TwoDigitYearMax = 2099;

                CultureInfo culture = (CultureInfo)CultureInfo.CurrentCulture.Clone();

                culture.DateTimeFormat.Calendar = cal;

                Thread.CurrentThread.CurrentCulture = culture;

        DateTime resultDate;

                        DateTime.TryParseExact("31012039",

                       "ddMMyyyy",

                       CultureInfo.CurrentCulture,

                       DateTimeStyles.None,

                       out resultDate);

        Foo foo = new Foo { 

            Date = resultDate 

        };

        JsonSerializerSettings settings =new JsonSerializerSettings()

        { 

            DateFormatHandling = DateFormatHandling.MicrosoftDateFormat, 

        DateTimeZoneHandling = DateTimeZoneHandling.Utc

        };

        //string json = JsonConvert.SerializeObject(foo, settings);

        string json = @"{ ""Date"" : ""\/Date(2180044800000)\/""}";

        Console.WriteLine(json);

        foo = JsonConvert.DeserializeObject<Foo>(json, settings);

        Console.WriteLine(foo.Date.ToLongDateString());

    }

}

​

class Foo

{

    public DateTime Date { get; set; }

}