In the eleventh year of Joram - The note in our margin contains as good an account of this chronological difficulty as can be reasonably required: Then he began to reign as viceroy to his father in his sickness; 2 Chronicles 21:18, 2 Chronicles 21:19. But in Joram's twelfth year he began to reign alone; 2 Kings 8:26.
In the eleventh year - The twelfth according to 2 Kings 8:25. The discrepancy may be best explained from two ways of reckoning the accession of Ahaziah, who is likely to have been regent for his father during at least one year. See 2 Chronicles 21:19.