Performing Tharpanam on every Amavasya (new moon day) is considered highly beneficial in Hinduism for several reasons:

• Blessings of Ancestors: It is believed that on Amavasya, the departed ancestors are more receptive to the offerings made by their descendants. Performing Tharpanam can appease them and invoke their blessings for the well-being of the family.
• Removal of Pitru Dosha: Pitru Dosha is a condition believed to arise from the unfulfilled desires or displeasure of ancestors. Regular Tharpanam, especially on Amavasya, is said to mitigate the negative effects of Pitru Dosha, which can affect various aspects of life like career, relationships, and finances.
• Fulfillment of Desires: By satisfying the ancestors through Tharpanam, it is believed that they, in turn, bless their descendants with the fulfillment of their righteous desires, including improvements in income, health, and marital harmony.
• Family Prosperity and Harmony: Tharpanam is thought to foster harmony and understanding within the family. Satisfied ancestors are believed to bless the family with prosperity, success, and balance.
• Mental Peace and Healing: Unresolved ancestral issues can sometimes lead to emotional disturbances. Performing Tharpanam can provide mental peace and healing by resolving these underlying issues.
• Blessings for Future Generations: The positive energy and blessings received from the ancestors through Tharpanam are also believed to benefit future generations, protecting them from negative influences and guiding them towards a bright future.
• Spiritual Progress: Tharpanam is considered a part of "Pitru Yagya," a way to honor and repay the debt to our ancestors, contributing to our spiritual growth.
• Protection from Negative Forces: Some believe that performing Tharpanam can ward off negative energies and evil influences.

Here's a breakdown of when Pitru Tharpanam is typically performed:

1. Amavasya (New Moon Days):

• Most Common: Pitru Tharpanam is primarily performed on every Amavasya (new moon) day of the Hindu lunar calendar. It's believed that on Amavasya, the Pitru Loka (ancestral realm) is more accessible, and offerings reach the ancestors easily.

  Monthly Offering: Many people perform it monthly on the Amavasya Tithi to appease their ancestors regularly and seek their continued blessings for material prosperity and spiritual progress.

2. Pitru Paksha (Fortnight of Ancestors):

• Most Significant: This 15-day period, usually in the Hindu month of Bhadrapada (September-October), is exclusively dedicated to honoring deceased ancestors. It is considered the most crucial time of the year for performing Shradh and Tharpanam rituals.

• Mahalaya Amavasya: The last day of Pitru Paksha, known as Mahalaya Amavasya or Sarvapitra Moksha Amavasya, is highly significant. If someone is unable to perform Shraddha on all the specific Tithis during Pitru Paksha, performing it on Mahalaya Amavasya is believed to appease all deceased souls in the family. It's also the day to perform Shraddha for those whose death anniversary Tithi is unknown.

3. Other Auspicious Occasions:

• Annual Shraddha (Death Anniversary): Pitru Tharpanam is an integral part of the annual Shraddha ceremony performed on the specific Tithi (lunar date) of the ancestor's demise.

• Solar and Lunar Eclipses (Grahaṇa Tharpanam): Performing Tharpanam during eclipses is considered highly meritorious.

  Sankranti: The beginning of certain Hindu months (Sankranti, especially Mesha, Karkidaga, Thula, and Makara Sankranti) are also considered auspicious for Tharpanam.

  Daily Rituals (Brahma Yagna Tharpanam): Traditionally, a form of Tharpanam was part of daily rituals to Devas, Rishis, and Pitrus.

• After Funeral Rites (Gunda Tharpanam): Performed in the first ten days after a death.

• Day After Annual Shraddha (Parheni Tharpanam): Though often performed on the same day as the annual Shraddha now.