What happens after the 12 months of Masikam are complete?

After 12 completed Masikams (plus any required Oona Masikams), the family performs Sapindikarana (called Sapindi Shradh in North India) — the ceremony on the 12th-month anniversary that merges the newly-departed soul into the collective ancestral line. At this ceremony, the single pinda offered for the deceased is merged with the pindas offered for the father, grandfather, and great-grandfather (Pita, Pitamaha, Prapitamaha). After Sapindikarana, the soul is believed to transition from the Preta state (wandering ghost) to the Pitri state (ancestral realm) and joins the lineage of liberated ancestors. From this point onwards, monthly Masikam is no longer required — only annual Shraddha on the death tithi and during Pitrupaksha are observed.