Thought from Today's Old Testament Passage:
Daniel 1:1 says that Nebuchadnezzar first invaded Palestine in the "third" year of Jehoiakim of Judah. But Jeremiah 46:2 says that the first year of Nebuchadnezzar was the "fourth" year of Jehoiakim. Which is right? Actually, both are right. Nebuchadnezzar was crowned king of Babylon in 605 B.C., which according to the Babylonian system would have been the "accession year" of Nebuchadnezzar. His first regnal year did not begin, therefore, until New Year's Day in 605. But according to the Judean system, the accession year counted as the first year of a king's reign. Since Jehoiakim was appointed king of Judah in 608 by Pharaoh Necho, 605 would be reckoned as his fourth year (which Jeremiah, as a resident of Jerusalem, would naturally have followed). But according to the Babylonian reckoning (which Daniel, as a resident of Babylon naturally followed), 605 would have been Jehoiakim's "third" year, (reckoning his first regnal year from New Year's Day 607). Hence both statements are correct, and both come out to the same year: 605—the year of Nebuchadnezzar's great victory at the Battle of Carchemish.
Gleason L. Archer, Encyclopedia of Bible Difficulties (Grand Rapids, MI: Zondervan, 1982), pp. 284-285.