Pachakkan Ashtmi Chaudas (Chaumasa Chaudas) is a Jain festival tied to the four-month Chaumasa period (monsoon season). Here’s the simple, authentic sense:

• What it is: Chaumasa Chaudas marks one of the four Chaudas observed during the Chaumasa vrata. It is a time for introspection, pratikraman (confession and repentance), and often a vow of additional restraint or fasting to grow in non-violence and self-purification. The tradition emphasizes staying focused on spiritual practices during the rainy season, when travel is discouraged to avoid harm to living beings.

• When it happens: The Chaumasa period begins with Ashadhi Purnima and ends with Kartik Purnima. In 2025, the ending is observed around Kartik Purnima, typically late Oct to early Nov (often noted as around Kartik Purnima). The end date for Chaumasa Chaudas for 2025 is commonly described in line with Kartik Purnima, with sources noting an ending date around early November. For the exact year-specific date, Jain calendars usually align with Kartik Purnima observations. You can read more about the end-date logic here.

• What to do: On Chaumas Chaudas, Jains may perform pratikraman, increase study of scriptures, and practice fasting or light asceticism to reduce karmic bondage and cultivate ahimsa.

• Digambar/Shvetambar note: The basic idea—practice repentance, restraint, and non-violence during Chaumasa—is common to both Digambar and Śvetāmbara communities, though specific rituals or emphasis can vary by sangh tradition.

You can read more about the importance and practice of Chaudas in Jainism here.