Answer

Nigod Nivaran Tap is commonly observed as a 25-upvas tapas. In many Jain sanghs, this is the standard count used for the tapa, while the exact vidhi can be set by the local acharya or sangh. ( jaincenterus.org)

Explanation

In Jain dharma, upvas is a form of anashan tapa—one of the external austerities. Tapas includes fasting and related disciplines such as unodari, vritti-sankshep, rasatyag, kayaklesh, and samlinata. Upvas is understood as a way of staying closer to the soul and reducing attachment to the body. ( jainfoundation.in)

The word Nigod refers to the lowest, microscopic form of life in Jain understanding, so this tapa is done with the भावना of nirjara, self-purification, and compassion for subtle life. ( jainworld.jainworld.com)

Practical Way

A simple way to understand it is:

• observe the prescribed number of upvas, usually 25; ( jaincenterus.org)
• keep your conduct pure during the tapa;
• follow the specific parna and vidhi given by your sangh or guru;
• do it with humility, not with pride.

Takeaway

So, in short: Nigod Nivaran Tap is generally done as 25 upvas, with the exact observance guided by your Jain sangh’s tradition. Its spirit is purification, restraint, and deep reverence for all life. ( jaincenterus.org)