Answer

Aatham and Chaudas depend on your city or region, because Jain tithis can vary by local panchang.

Explanation

If you want the next Aatham and next Chaudas for fasting or observance, I need your city/country to give the correct dates.

Spiritual Understanding

In Jain Dharma, observing tithis with proper timing is important, so the local calendar matters.

Takeaway

Please share your location so I can tell you the next exact Aatham and Chaudas.