Regnal year dating
The first thing that needs to be established is when the regnal year of a king starts.
Many may be familiar with the fact that Israel had two calendars; a civil calendar beginning with the month Tishri, and a religious or sacred calendar beginning with the month Nisan, previously Aviv or Abib.
And in the fourth month, in the ninth day of the month, the famine was severe in the city, so that there was no bread for the people of the land.
Then the city was broken up, and all the men of war fled, and went forth out of the city by night." Jerusalem was captured in the fourth month of Zedekiah's eleventh year.
This would be the same for Hoshea's 7th year and 9th year.
What this does tell us is that at this time both Judah and Israel were using the same regnal year system.
The beginning of these calendars are six months apart, and when the regnal year of a particular king starts can be a very important issue.
It would be even more complicated if Judah used a Nisan to Nisan regnal year, and the northern kingdom of Israel used a Tishri to Tishri regnal year, as the same event would be recorded by two different people as happening at different times according to their different time systems.
This evidence indicates that before the divided kingdom, Solomon's regnal year was reckoned from Nisan to Nisan.
For they could not keep it at that time, because the priests had not sanctified themselves sufficiently, neither had the people gathered themselves together to Jerusalem.
(2 Chronicles ) "And there assembled at Jerusalem many people to keep the feast of unleavened bread in the second month, a very great congregation." The Passover was usually kept on the 14th Nisan the first month of the year, but there was a provision for it to be kept in certain circumstances on the 14th of the second month.
This is a bible study which investigates the regnal years of the Hebrew kings in scripture.
Regardless of which regnal year system scholars seem to prefer, they all seem to agree that since God told Moses that Nisan would be the first month (Exodus 12:2), the months are numbered from Nisan, not Tishri. (Esther 3:7) "In the first month, which is the month of Nisan." (Esther 8:9) "So the king's scribes were called at that time, in the third month, which the month of Sivan." (1 Kings 6:1) "in the fourth year of Solomon’s reign over Israel, in the month Ziv, which is the second month, that he began to build the house of Yahweh." (1 Kings ) "And in the eleventh year, in the month Bul, which is the eighth month, was the house finished throughout all its parts." (1 Kings 8:2) "the feast in the month of Ethanim (Tishri), which of the ninth month, Chislev." Concerning the kings before the divided kingdom, the evidence points to the regnal year being from Nisan to Nisan. (1 Kings 6:1) "in the fourth year of Solomon’s reign over Israel, in the month Ziv, which is the second month, that he began to build the house of Yahweh." (1 Kings -38) "In the fourth year the foundation of the house of Yahweh was laid, in the month Ziv, And in the eleventh year, in the month of Bul, which is the eighth month the house was finished in all its details according to all its plans.