Albert Barnes Commentary 2 Chronicles 28:1

"Ahaz was twenty years old when he began to reign; and he reigned sixteen years in Jerusalem: and he did not that which was right in the eyes of Jehovah, like David his father;" — 2 Chronicles 28:1 (ASV)

This chapter is supplemental in character. The writer seems to assume that the reader is familiar with the narrative in the book of Kings and is mainly concerned with adding points that the author of that account has omitted.