Parivartana Yoga is a mutual exchange of signs: the lord of one house occupies a second house, while the lord of that second house occupies the first, so that each planet sits in the other's domicile. It is the Indian equivalent of what western traditional astrology calls mutual reception, and it is read as binding the affairs of the two houses together, so that the matters of one cannot be advanced without the other. The classical treatment divides exchanges into three classes: maha or great, between benefic houses; kahala, involving mixed houses; and dainya, involving the difficult sixth, eighth and twelfth, which is read unfavourably. The technique is one of the clearest and most useful in the system precisely because it is structural: it depends only on the placement of the two lords and not on any judgment of strength, so it is unambiguous where much else is not.
One frequently named special case is the Dharma-Karmadhipati Yoga, formed specifically when the lords of the ninth and tenth houses, dharma and karma, fortune and action, are connected by conjunction, mutual aspect or exchange; because it always draws on one house from the upper trine and one from the kendras, it is treated by many commentators as inherently a maha parivartana when the connection takes the form of a sign exchange, and it is one of the most consistently praised yogas in the classical literature for combining ethical standing with visible achievement. An exchange involving the lord of the Ascendant itself is likewise given extra weight beyond the ordinary maha/kahala/dainya grading, on the reasoning that the first house governs the native's whole constitution, so whatever house its lord is bound to by exchange is drawn close to the core of the life.