We have to perform Sharartham (or) Thithi on a particular thithi day, of when death happened. Day will vary each year. We have to perform pooja , serve food and if possible donate clothes for the needy one on the particular day to get the blessing from our deceased people..
For the deceased great parents, great grand parents or Husband or Wife or Children we should give Sharartham ( or) Thithi annually without fail to get the blessings of them. The Regular Tharpanams one has to perform.
Apart from the listed days here under, one has to perform the TharppaNam on the Eclipse days and also on the next day to Mathru/Pithru Srardha days: To come to the reality and practicability, one has to read the entire Srardha Niyama and the reasoning for it. According to the Vaidhyanatheeyam and Srivaishnava Deepika, a dutiful Brahmin has to perform 96 tharppanams in a year, as stipulated in the Vedic scripts. Listed below are the days on which a Brahmin has to perform his duty in Thila tharpaNa roopam. Out of these, the Mahalaya Tharpanam can be done with Hiranyam or with BrahmmaNa bhojanam also; if not on all the sixteen day, any one day that one considers himself as most important – viz. Mahabharani, Madhyashtami or on his mathru/ pithru srardha thithi days that falls during Mahalayam. Amavasya - 12 Masapirappu - 12 Pournami - 12 Kruthayugathi - 1 Threthayugathi - 1 Dwaparayugathi - 1 Kaliyugathi - 1 Vaithruthi Yogas - 14 Vyatheepatha Yoga -14 Mahalayathi -16 Ashtaka - 4 Anvashtaka - 4 Thisroshtaka -4
If one cannot afford to perform the Tharsha Srardham known as Thila tharppaNam on all the above days, one should stick to minimum possible on Amavasya, Mesha Sangramanam, DakshinayaNa punyakaalam, Thula Vishu Punyakalam, UtharayaNa punyakalam, visible Surya/Chandra Grahan days and also on the next days to Mathru/Pithru srardha.