In the Jain calendar, Varshitap in 2026 is tied to these tithis:

• Start (Sankalp):

Fagan / Falgun Krishna Ashtami (Falgun Vad 8) In many Panchang (e.g. used in UK/India), this falls on Wednesday, 11 March 2026.

• Parna (Completion):

Vaishakh Shukla Tritiya (Vaishakh Sud 3, Akshaya Tritiya) This falls on Monday, 20 April 2026 in many places.

However:

• Some traditions and Panchang calculations may treat Chaitra Shukla Ashtami as the effective start point for Varshitap in 2026.
• Exact English dates can change slightly by country, city and the Panchang/derasar you follow.

So, the safe and traditional way is:

1. Take Varshitap sankalp on Falgun Krishna Ashtami (around 11 March 2026) as per your local Jain Panchang.
2. Do parna on Vaishakh Shukla Tritiya (Akshaya Tritiya, around 20 April 2026) according to that same Panchang.

For a simple explanation based on the Jain calendar you can also see this answer on JainKnowledge

Please confirm final dates with your local Jain Panchang or derasar, as that is considered the deciding authority.