In Jain Dharma, Chaturmas (Chaumasa) does not start on a fixed English (Gregorian) date. It is based on the lunar tithi:

• Start of Chaturmas:

Āṣāḍh Śukla Ekādashi (Ashadh Sud 11), also called Devshayanī/Devshayani Gyaras

• End of Chaturmas:

Kārtik Śukla Ekādashi (Kartik Sud 11), also called Prabodhini/Devuthānī Gyaras

So Chaturmas always begins on Ashadh Sud 11 and ends on Kartik Sud 11; the exact English dates change every year according to the Jain/Vikram Samvat calendar.

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