Q: WHAT YEAR DID AHAZIAH'S REIGN END IN JUDAH?
A: IT DEPENDS WHAT CALENDAR YOU ARE USING!
On the Gregorian calendar (the one you might have on your wall) the year was 826 BC.
On the Hebrew calendar, sometimes called the biblical calendar, the year was 3221 AM.
2 Kings 8:25-26 – In the twelfth year of Joram the son of Ahab king of Israel did Ahaziah the son of Jehoram king of Judah begin to reign. Two and twenty years old was Ahaziah when he began to reign; and he reigned one year in Jerusalem. And his mother's name was Athaliah, the daughter of Omri king of Israel.
2 Kings 11:3 New King James Version (NKJV)
3 So he was hidden with her in the house of the Lord for six years, while Athaliah reigned over the land.