Siddhi Tap is a type of tapas or spiritual practice observed by Jain ascetics during the four-month period of chaumasa in Jain religion. It involves fasting for 44 days, during which the actual fasting days are 36, and the person survives only on boiled water taken between sunrise and sunset. The Siddhi Tap is spread over 44 days with breaks in between, and a person on Siddhi Tap is given one meal after fasting for a day, and the next meal is taken after a gap of two days. The practice is considered one of the greatest tapas done by many Jain ascetics.