Is it okay to write couplets vertically in the calligraphy competition?

Of course. According to official website, whoever inquires about lightning news, the calligraphy works must be four feet or six feet vertical, and the screens, couplets and hats are not accepted. If they are not submitted as required, they will not be selected. The works will be mounted and exhibited by the organizer, and all the works will be returned after the exhibition, so it is ok to write couplets vertically in the calligraphy competition.