Choumasu / Chaturmas 2026 in Jain tradition is commonly observed as starting on 28 July 2026. In JainKnowledge’s 2026 Jain calendar, this is listed as Ashadh Sud 14. ( atmadharma.com)

The ending is local-tradition dependent; JainKnowledge notes that in many regional calendars it runs roughly from late July 2026 to late November 2026, ending around Kartik Shukla Ekadashi. ( jainknowledge.com)

So, the practical Jain observance window for 2026 is:

• Start: 28 July 2026
• End: around late November 2026, depending on your sangh / panchang. ( atmadharma.com)