After how many thithis must the yearly ceremony of a dead person (Tamil) be performed ?

Answer: Normally, the same thithi/month is to be followed in the immediate next year. In some cases, there can be one or two extra thithis known as adhika masyam; if there are two thithis falling in the same month of aabdeekam known as first year ceremony, then the later is to be taken. It all depends on the remainder thithi timing specific day in the following year & month. In some cases, it can fall in the exact 12th month itself, and in some it may be the 13th month. The one general condition is, the month & thithi should be same that of the moksha day.