You are a cash-basis taxpayer, so it should be reportable in the year you receive it but the answer is even more simple than that. It is the dividend paying company's obligation to add the dividends to the correct year's 1099-DIV so I would only pay attention to what is reported on the 1099-DIV. If they sent you a "corrected" 1099-DIV, then you might need to amend your return. If not, you can assume the will report it in the proper year. This answer posted by a CPA.
