I have extension method on DateTime class:

```
public static DateTime? SafeConvertToDateTime(this string value, bool dateOnly)
{
    DateTime parsedDateTime;
    if (DateTime.TryParse(value, out parsedDateTime))
    {
        return DateTime.SpecifyKind(parsedDateTime, DateTimeKind.Utc);
    } else {
        return new DateTime(1, 1, 1, 0, 0, 0, DateTimeKind.Utc);
    }
}

```

If "dateOnly=true" i should return Datetime with only Date property and all conversions later on client (to local or utc) should be skipped if there is DateTime with only Date.
But how can i know that this DateTime holds only Date(since time can be valid as 0)? 
I could add extension property (dateOnly), but as I know, I can't add extension property in C#, only methods?
Can I use some existing property of Datetime to tell, there is only date which should be consider later in code?