Is my Hajj valid even though I did not shave my head until the eleventh day of Dhu al-Hijjah out of negligence? And do I owe an expiation?

The majority of scholars hold that shaving (or cutting) the hair is a ritual act in Hajj and Umrah (definition). There is no objection to delaying it until the last of the days of sacrifice, by agreement among the jurists. What extends beyond that is a point of contention: some scholars say there is no consequence, while others say it necessitates a blood sacrifice (dam). Delaying the shaving does not entail anything.