In Jainism, the Varshitap is a special and highly revered austerity involving alternate day fasting, usually performed over a period of one year. The Varshitap is traditionally started on the 8th day of the bright half of the Chaitra month (Chaitra Shukla Ashtami) according to the Jain calendar, which generally falls in March or April of the Gregorian calendar.

The austerity concludes on Akshaya Tritiya (the 3rd day of the bright half of Vaishakha month), which is a very auspicious day in Jain tradition. This day marks the anniversary when Lord Rishabhanatha (Adinath), the first Tirthankara, ended his year-long fast by consuming sugarcane juice.

So, Varshitap starts on Chaitra Shukla Ashtami and ends on Vaishakh Shukla Tritiya (Akshaya Tritiya) each year. The exact dates vary according to the lunar calendar.