The board of directors declared a $2.30 per-share cash dividend payable on January 14 to stockholders of record on December 26. No previous entries were done for dividends payable or declared dividends. Do I need to do an adjusting entry?

On Dec 26 you need to record the dividends declared and your Credit will be to dividends payable. Your amount will be $2.30 times number of shares outstanding at Dec 26.