Sarpashapa Yoga comes under the special category of arishta yogas or bad yogas in Hindu astrology. According to the standard texts, this Yoga comes into operation under the following conditions.
If the 5th house in the natal chart is occupied by Rahu and aspected by Kuja (Mars), or the 5th house being a sign of Mars is occupied by Rahu.
If the 5th lord is in conjunction with Rahu and Saturn is in the 5th house aspected by or associated with Mars.
If the karaka (significator) of children, viz., Jupiter, is in association with Mars, Rahu in lagna (1st house0 and the 5th lord is in a dushtasthana (bad house, like the 6th, 8th or the 12th)
If the 5th house, being a sign of Mars (Aries or Scorpio), is conjoined with Rahu and is aspected by or associated with Mercury.
The result of this yoga is that there will be death of children due to the curse of the serpents.
It must be noted that the common factor in all the four conditions of this yoga is the affliction of the 5th bhava, karaka or the lord of children’s house by Rahu. According to the first condition, either the 5th house should be occupied by Rahu and aspected by Mars or the 5th house, happening to be ruled by Mars (Aries or Scorpio), should have the association of Rahu. The latter part of the combination which is of a more general nature, is suggestive of severe affliction to the 5th house. In other words, the 5th Lord must join Rahu, ad Saturn must be in the 5th having the aspect or conjunction with the Moon. The fourth combination is merely a repetition of the earlier combination with the difference that here Mercury is brought in and its aspect or association made a condition for the presence of this yoga, which is also called Sarpasapat Sukakshya Yoga.