All these tests pass "successfully":

Assert.AreEqual(TimeSpan.Parse("0:00:00.0123456"), TimeSpan.Parse("0:00:00.00123456")); Assert.AreEqual(TimeSpan.Parse("0:00:00.0123456").Ticks, 123456); Assert.AreEqual(TimeSpan.Parse("0:00:00.00123456").Ticks, 123456); 

and these

Assert.AreEqual(TimeSpan.Parse("0:00:00.00000098").Ticks, 98); // (no exception thrown) Assert.ThrowsException<OverflowException>(() => TimeSpan.Parse("0:00:00.00000099")); 

*edit: dropped a (non-code) letter