[HttpPost]
        public ResultBase<ResultEnum> EditRate(RateCurrencyModel rate )
......

 public class RateCurrencyModel
    {
        public int Id { get; set; }
        public int CurrencyId { get; set; }
        public DateTime Date { get; set; }
}

      
System.Web.Mvc.ModelBinders.Binders.Add( typeof( DateTime ), new DateTimeModelBinder() );
System.Web.Mvc.ModelBinders.Binders.Add( typeof( DateTime? ), new DateTimeModelBinder() );