If you mean Paryushan, the 2026 dates depend on the Jain tradition:
Śvetāmbara Paryushan: Tuesday, September 8, 2026 to Tuesday, September 15, 2026. Samvatsari is on September 15, 2026. ( msjs.org.au)
Digambara Das Lakshan Mahaparva: Wednesday, September 16, 2026 to Friday, September 25, 2026. ( jaincentermn.org)
Explanation
Many Jain calendars list the full 2026 observance period from September 8 to September 25, 2026, covering Śvetāmbara Paryushan and Digambara Das Lakshan together. ( jcnc.org)
Spiritual Understanding
Paryushan is a very sacred time for introspection, fasting, forgiveness, and आत्मशुद्धि. In the Śvetāmbara tradition, the last day is Samvatsari, the day of asking forgiveness. ( msjs.org.au)
Takeaway
For 2026, the safest simple answer is: Paryushan begins on September 8, 2026, and the main observance continues through September 15, 2026 for Śvetāmbara Jains. ( msjs.org.au)