Although there exists a leap July according to the leap month under the old calendar, July 7 of the leap month is not the day of tanabata because no annual events are traditionally held in a leap month.
なお、旧暦の場合、閏月の関係で閏7月になることもあるが、閏月に年中行事は行わないため、閏7月7日は旧七夕とはならない。