Answer

Samvatsari and Ganpati day usually do not fall on the same day because they belong to different religious calendar systems and traditions.

• Samvatsari is observed by Jains on Bhadrapad Shukla Panchami according to the Jain lunar calendar, at the end of Paryushan.
• Ganesh Chaturthi is observed by Hindus on Bhadrapad Shukla Chaturthi.

So traditionally, Ganesh Chaturthi comes one tithi before Samvatsari. That is why Samvatsari is generally not on Ganpati day.

Explanation

In simple words:

• Ganpati day = Chaturthi tithi
• Samvatsari = Panchami tithi

Since Chaturthi and Panchami are different lunar dates, they normally fall on different civil calendar days.

Sometimes, due to the way lunar tithis begin and end, a tithi can overlap sunrise or change during the day. Because of this, festival dates may occasionally appear close together or confusing in printed calendars. But from the Jain religious perspective, Samvatsari is tied to the proper Jain observance of Paryushan and Panchami.

Spiritual Understanding

Samvatsari is the most important day of forgiveness in the Jain year. It is connected with:

• Pratikraman
• Alochana
• Pratyakhyan
• Kshamapana
• Micchami Dukkadam

Its focus is not on matching another festival day, but on inner purification, repentance, forgiveness, and reducing karmic bondage.

Takeaway

Samvatsari is not on Ganpati day because Ganesh Chaturthi is Chaturthi, while Samvatsari is Panchami. They are adjacent tithis, not the same tithi.