Here are the January 2018 Amavasya Tharpanam Sankalpam Mantras for Sarva Amavasya. 16 January 2018 is Sarva Amavasya.
16 January 2018 is – Pushya Amavasya, Magha Amavasya, Thai Amavasai and Makara masa Amavasya as per Amavasyant Chandramana Panchang, North Indian Hindi calendars, Tamil and Malayalam calendars respectively.
16 January 2018 – Sarva Amavasya
Hevilambinama samvathsare ,Utharayane , hemantha rithou, makara mase , Krishna pakshe, adhya amavasyam punya thidhou , bhouma vasara yukthayam, Poorvashada nakshatra yukthayam, shubhayoga, shubhaKarana evam guna viseshena, visishtayam asyam amavasyam punya thidhou, amavasya punyakale, darsa sradham , thilatharpana roopena adhya karishye
(Amavasya up till 2.49 AM next morning (Prathama afterwards) and Poorvashada Nakshtra up to 7.23 PM (afterwards Uthrashada))