Explainers debate whether in the second year of Darius the king
belongs with Haggai 1:15 or Haggai 2:1. Those who say it belongs with Haggai 2:1 observe that all of the other dating notices in the prophecy include the year (1:1, 2:10; 2:20 does not include the year likely because the message that follows was delivered on the same day as the message following Haggai 2:10, and so there is no need to give the year in that instance). So one should expect a similar approach in the dating notice in Haggai 2:1 (see NRSV), as it should match with what we find in Haggai 1:1 and Haggai 2:10.1,2
Those who see it as belonging with Haggai 1:15 see it as an inclusion device, an end bracket, a mirror of the date formula in Haggai 1:1, wherein Haggai 1:1 uses the order year-month-day and Haggai 1:15 uses the order day-month-year.3 It seems that Meyers and Meyers offer the best proposal in this regard. They maintain that the date serves double duty: since both messages (Haggai 1:1–11 and Haggai 2:1–9) happen in the same year, the dating formula here functions as a bridge between the two narratives, bringing Haggai 1:1–14 to a conclusion and serving as an opening of Haggai 2:1–9.4,5 Thus, it is best to follow the traditional verse division and take this with what precedes it.
15 on the twenty-fourth day of the month, in the sixth month, in the second year of Darius the king.