A Tithi is formed when Sun moves 12 degrees forward from its position. Sun is the lord of Saptmi Tithi. Each Paksha has one Saptami Tithi.
Saptami Tithi when occurring on Saturday forms an inauspicious Yoga. This Yoga is called Karkach Yoga. During this time, no auspicious work is done. This Tithi forms Mirtyu Yoga when occurring on Monday and Saturday. Saptami Tithi forms a Siddhi Yoga when occurring on Wednesday.
Mirtyu Yoga is an inauspicious Yoga, whereas, Siddhi Yoga is an auspicious Yoga. All works done in Siddhi Yoga get completed. This Tithi is not used for marriage as, Sun is the lord of this date. Performing marriage on this date can create problems in married life of the couple.
Person born on Saptami Tithi has a nature of satisfaction. He is of magnificent personality. And, he gets success in works done by intelligence. This Yoga increases luck of a person and he has versatile qualities. Also, he gets the happiness of wealth and child.