Annual shraddham has to be done with homam and three bhokta-s. In the varshAptikam, kartA need not perform parehanee tharppanam the following day. But must perform a tadheeyaradhanam and feed Brahmins.
In the varhshAptikam, a bhoktA must not partake in a shraddha 3 days after varshAptikam. Must do 300 Gayatri mantra japam.