I am not sure that leap seconds are taken into account on the .NET side of things. I created a simple Visual FoxPro 8 COM server, which was set to take datetime in ANSI format only (YYYY.MM.DD HH:MM:SS). In C#, I noted the value from System.DateTime.Now, then converted it with System.DateTime.Now.Ticks, passed the Ticks string to VFP, converted it back to DateTime() in VFP, and the result datetime was several seconds different than what I began with.