saving/Comparing Date from C# to Sql

when date as  String and pass it to StoredProcedure. 

Convert.ToDateTime(model.ToDate, cultureinfo).ToString("yyyy-MM-dd HH:mm:ss.fff")

where ToDate is string in Code and DateTime in SP

For Comparison

where FromDate is Datetime in code

obj.FromDate = DateTime.ParseExact(dates1, "dd/MM/yyyy", cultureinfo);

In SP

Compre Dates

BETWEEN CAST(CONVERT(varchar, ISNULL(@FromDate, GETDATE() - 365), 112) AS int) AND CAST(CONVERT(varchar, ISNULL(@ToDate, GETDATE()), 112) AS int)