Varshitap every year starts on the tithi:

फाल्गुन वद अष्टमी (Fagan/Falgun Vad Aatham) = Falgun Krishna Ashtami (8th day of the dark half of Falgun)

In some calendars this same tithi is written as Chaitra Krishna Ashtami, but the Jain rule is: Varshitap Arambh = Falgun Vad Aatham and it then concludes on Vaishakh Sud 3 (Akshaya Tritiya) with parna.

The exact English (Gregorian) date changes every year, so you should always confirm it from your local Jain panchang or sangh.

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